GHA: Fix Windows build?

Author: nicowilliams

.github/actions/get-msys2/action.yml

@@ -31,11 +31,12 @@ runs:
   steps:
     - name: 'Install MSYS2'
       # use a specific release of msys2/setup-msys2 to prevent jtreg build failures on newer release
-      uses: msys2/setup-msys2@7efe20baefed56359985e327d329042cde2434ff
+      uses: msys2/setup-msys2@v2
       with:
-        install: 'autoconf tar unzip zip make'
+        install: 'base-devel git autoconf tar unzip zip make'
         path-type: minimal
         location: ${{ runner.tool_cache }}/msys2
+        update: true
 
       # We can't run bash until this is completed, so stick with pwsh
     - name: 'Set MSYS2 path'