[clang] [libclang/python] Ignore our own DeprecationWarnings in CMake targets (PR #178631)

[Jannick Kremer via cfe-commits]

DeinAlptraum wrote:

Fair enough. The context manager is targeted enough I guess, so I changed it to that.
Note that we can't use the `cateegory=` argument (and most of the other filters) since they were only added in Python 3.11

https://github.com/llvm/llvm-project/pull/178631