[python] Bump Python minimum version to 3.7

As per the RFC
https://discourse.llvm.org/t/rfc-upgrading-llvms-minimum-required-python-version/67571,
raise the minimum Python version to ensure that the Python syntax doesn't
become overly obsolete, to enable new Python feature usage, and ensure the
maintainability of CI.

Author: linux4life798

llvm/CMakeLists.txt

@@ -880,8 +880,8 @@ set(LLVM_PROFDATA_FILE "" CACHE FILEPATH
   "Profiling data file to use when compiling in order to improve runtime performance.")
 
 if(LLVM_INCLUDE_TESTS)
-  # Lit test suite requires at least python 3.6
-  set(LLVM_MINIMUM_PYTHON_VERSION 3.6)
+  # All LLVM Python files should be compatible down to this minimum version.
+  set(LLVM_MINIMUM_PYTHON_VERSION 3.7)
 else()
   # FIXME: it is unknown if this is the actual minimum bound
   set(LLVM_MINIMUM_PYTHON_VERSION 3.0)

llvm/docs/GettingStarted.rst

@@ -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/>`_                          >=3.7        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.
    #. Optional, adds compression / uncompression capabilities to selected LLVM
       tools.
    #. Optional, you can use any other build tool supported by CMake.