gh-125398: Convert paths in venv activate script when using Git Bash under Windows (GH-125399)

* Convert paths in venv activate script when using Git Bash under Windows

With #112508 the check to converts paths when running on Windows was changed from using the non-posix environment variable `$OSTYPE` to using `uname` instead.

However this missed the fact that when running under Git Bash on Windows, uname reports `MINGW*` (`$OSTYPE` is still `msys`).

This results in `$PATH` being set to something like `D:\a\github-actions-shells\github-actions-shells\venv/Scripts:…`, instead of `/d/a/github-actions-shells/github-actions-shells/venv/Scripts`.

Notably, the Git Bash is the bash shell that’s used for GitHub Actions Windows runners, and ships with VSCode.

Author: julienp

Lib/venv/scripts/common/activate

@@ -38,8 +38,8 @@ deactivate nondestructive
 
 # on Windows, a path can contain colons and backslashes and has to be converted:
 case "$(uname)" in
-    CYGWIN*|MSYS*)
-        # transform D:\path\to\venv to /d/path/to/venv on MSYS
+    CYGWIN*|MSYS*|MINGW*)
+        # transform D:\path\to\venv to /d/path/to/venv on MSYS and MINGW
         # and to /cygdrive/d/path/to/venv on Cygwin
         VIRTUAL_ENV=$(cygpath "__VENV_DIR__")
         export VIRTUAL_ENV

Misc/NEWS.d/next/Library/2024-10-13-15-04-58.gh-issue-125398.UW7Ndv.rst

@@ -0,0 +1 @@
+Fix the conversion of the :envvar:`!VIRTUAL_ENV` path in the activate script in :mod:`venv` when running in Git Bash for Windows.