[llvm] [python] Bump Python minimum version to 3.8 (PR #78828)

[Aiden Grossman via llvm-commits]

================
@@ -286,15 +286,15 @@ uses the package and provides other details.
 Package                                                     Version      Notes
 =========================================================== ============ ==========================================
 `CMake <http://cmake.org/>`__                               >=3.20.0     Makefile/workspace generator
-`python <http://www.python.org/>`_                          >=3.6        Automated test suite\ :sup:`1`
+`python <http://www.python.org/>`_                          >=3.8        Automated test suite\ :sup:`1`
 `zlib <http://zlib.net>`_                                   >=1.2.3.4    Compression library\ :sup:`2`
 `GNU Make <http://savannah.gnu.org/projects/make>`_         3.79, 3.79.1 Makefile/build processor\ :sup:`3`
 =========================================================== ============ ==========================================
 
 .. note::
 
    #. Only needed if you want to run the automated test suite in the
-      ``llvm/test`` directory.
+      ``llvm/test`` directory or the libclang Python binding unit tests.
----------------
boomanaiden154 wrote:

I'd mention bindings in their too and then I think that should pretty much cover everything:
```
...or if you plan to utilize any Python libraries, utilities, or bindings.
```

https://github.com/llvm/llvm-project/pull/78828