Exclude MSVC up to 19.16 from using std::launder (#5968)

* Exclude further MSVC versions from std::launder

Versions 19.4, 19.5 and 19.6 now also excluded. Error seen with 19.6, error triggered by this commit:
57b9a0a

_deps\fetchedpybind11-src\include\pybind11\pybind11.h(3008): fatal error C1001: An internal error has occurred in the compiler. [C:\projects\openpmd-api\build\openPMD.py.vcxproj]
  (compiler file 'd:\agent\_work\8\s\src\vctools\compiler\utc\src\p2\main.c', line 187)
   To work around this problem, try simplifying or changing the program near the locations listed above.
  Please choose the Technical Support command on the Visual C++
   Help menu, or open the Technical Support help file for more information

* Add minimal comment // See PR #5968

---------

Co-authored-by: Ralf W. Grosse-Kunstleve <rgrossekunst@nvidia.com>

Author: franzpoeschel

include/pybind11/detail/common.h

@@ -87,7 +87,7 @@
 #    endif
 #endif
 
-#if defined(__cpp_lib_launder) && !(defined(_MSC_VER) && (_MSC_VER < 1914))
+#if defined(__cpp_lib_launder) && !(defined(_MSC_VER) && (_MSC_VER < 1920)) // See PR #5968
 #    define PYBIND11_STD_LAUNDER std::launder
 #    define PYBIND11_HAS_STD_LAUNDER 1
 #else