[llvm] [Dexter] Remove outdated imp dependency (PR #111833)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-sie-win` running on `sie-win-worker` while building `cross-project-tests` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/46/builds/6256

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'cross-project-tests :: debuginfo-tests/dexter/feature_tests/commands/penalty/float_range_zero_nonmatch.cpp' FAILED ********************
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 7
clang-cl /Zi /Od Z:\b\llvm-clang-x86_64-sie-win\llvm-project\cross-project-tests\debuginfo-tests\dexter\feature_tests\commands\penalty\float_range_zero_nonmatch.cpp -o Z:\b\llvm-clang-x86_64-sie-win\build\projects\cross-project-tests\debuginfo-tests\dexter\feature_tests\commands\penalty\Output\float_range_zero_nonmatch.cpp.tmp
# executed command: clang-cl /Zi /Od 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\cross-project-tests\debuginfo-tests\dexter\feature_tests\commands\penalty\float_range_zero_nonmatch.cpp' -o 'Z:\b\llvm-clang-x86_64-sie-win\build\projects\cross-project-tests\debuginfo-tests\dexter\feature_tests\commands\penalty\Output\float_range_zero_nonmatch.cpp.tmp'
# RUN: at line 8
not "C:\Program Files\Python310\python.exe" "Z:/b/llvm-clang-x86_64-sie-win/llvm-project/cross-project-tests\debuginfo-tests\dexter\dexter.py" test --fail-lt 1.0 -w --debugger dbgeng --binary Z:\b\llvm-clang-x86_64-sie-win\build\projects\cross-project-tests\debuginfo-tests\dexter\feature_tests\commands\penalty\Output\float_range_zero_nonmatch.cpp.tmp -- Z:\b\llvm-clang-x86_64-sie-win\llvm-project\cross-project-tests\debuginfo-tests\dexter\feature_tests\commands\penalty\float_range_zero_nonmatch.cpp | z:\b\llvm-clang-x86_64-sie-win\build\bin\filecheck.exe Z:\b\llvm-clang-x86_64-sie-win\llvm-project\cross-project-tests\debuginfo-tests\dexter\feature_tests\commands\penalty\float_range_zero_nonmatch.cpp
# executed command: not 'C:\Program Files\Python310\python.exe' 'Z:/b/llvm-clang-x86_64-sie-win/llvm-project/cross-project-tests\debuginfo-tests\dexter\dexter.py' test --fail-lt 1.0 -w --debugger dbgeng --binary 'Z:\b\llvm-clang-x86_64-sie-win\build\projects\cross-project-tests\debuginfo-tests\dexter\feature_tests\commands\penalty\Output\float_range_zero_nonmatch.cpp.tmp' -- 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\cross-project-tests\debuginfo-tests\dexter\feature_tests\commands\penalty\float_range_zero_nonmatch.cpp'
# .---command stderr------------
# | 
# | 
# | ****************************************
# | ****************************************
# | ****************************************
# | **                                    **
# | ** This is a bug in DExTer.           **
# | **                                    **
# | **                  Please report it. **
# | **                                    **
# | ****************************************
# | ****************************************
# | ****************************************
# | 
# | system:
# | win32
# | 
# | version:
# | DExTer 1.0.0 [main 6779376ee917279b16e256839d236cfdf8fd9ab9] (https://github.com/llvm/llvm-project.git)
# |   using Python 3.10.5 (tags/v3.10.5:f377153, Jun  6 2022, 16:14:13) [MSC v.1929 64 bit (AMD64)]
# | 
# | args:
# | ['c:\\program files\\python310\\python.exe', 'Z:/b/llvm-clang-x86_64-sie-win/llvm-project/cross-project-tests\\debuginfo-tests\\dexter\\dexter.py', 'test', '--fail-lt', '1.0', '-w', '--debugger', 'dbgeng', '--binary', 'Z:\\b\\llvm-clang-x86_64-sie-win\\build\\projects\\cross-project-tests\\debuginfo-tests\\dexter\\feature_tests\\commands\\penalty\\Output\\float_range_zero_nonmatch.cpp.tmp', '--', 'Z:\\b\\llvm-clang-x86_64-sie-win\\llvm-project\\cross-project-tests\\debuginfo-tests\\dexter\\feature_tests\\commands\\penalty\\float_range_zero_nonmatch.cpp']
# | 
# | Traceback (most recent call last):
# |   File "Z:\b\llvm-clang-x86_64-sie-win\llvm-project\cross-project-tests\debuginfo-tests\dexter\dexter.py", line 20, in <module>
# |     return_code = main()
# |   File "Z:\b\llvm-clang-x86_64-sie-win\llvm-project\cross-project-tests\debuginfo-tests\dexter\dex\tools\Main.py", line 203, in main
# |     module = _import_tool_module(tool_name)
# |   File "Z:\b\llvm-clang-x86_64-sie-win\llvm-project\cross-project-tests\debuginfo-tests\dexter\dex\tools\Main.py", line 138, in _import_tool_module
# |     return load_module(tool_name, tools_directory)
# |   File "Z:\b\llvm-clang-x86_64-sie-win\llvm-project\cross-project-tests\debuginfo-tests\dexter\dex\utils\Imports.py", line 7, in load_module
# |     spec = importlib.util.spec_from_file_location(
# | AttributeError: module 'importlib' has no attribute 'util'
# `-----------------------------
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\filecheck.exe' 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\cross-project-tests\debuginfo-tests\dexter\feature_tests\commands\penalty\float_range_zero_nonmatch.cpp'
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
...

```

</details>

https://github.com/llvm/llvm-project/pull/111833