cmake: Do not pin exact Python patch version in pxrConfig.cmake

In `pxrConfig.cmake.in`, CMake was looking for exactly
the same Python version used to build OpenUSD, so if a
OpenUSD was built against Python 3.11.3,
`find_package(pxr REQUIRED)` would fail on a machine
with Python 3.11.5, even if different patch versions of
Python are ABI compatible if the minor version is the
same, see https://docs.python.org/3/c-api/stable.html .

This PR fixes downstream problems such as OpenMoonRay/openmoonray#141 and
conda-forge/openusd-feedstock#11 .

Closes PixarAnimationStudios#3759

(Internal change: 2409381)

Author: traversaro

pxr/pxrConfig.cmake.in

@@ -43,7 +43,7 @@ if(@PXR_ENABLE_PYTHON_SUPPORT@)
     endif()
 
     if (NOT DEFINED Python3_VERSION)
-        find_dependency(Python3 "@Python3_VERSION@" EXACT COMPONENTS Development)
+        find_dependency(Python3 "@Python3_VERSION_MAJOR@.@Python3_VERSION_MINOR@" EXACT COMPONENTS Development)
     else()
         find_dependency(Python3 COMPONENTS Development)
     endif()