Display opam version

Author: dra27

.github/workflows/windows.yml

@@ -34,6 +34,7 @@ jobs:
 
       - name: Add opam to PATH
         run: |
+          D:\opam\bin\opam --version
           "D:\opam\bin" | Out-File -FilePath $env:GITHUB_PATH -Encoding utf8 -Append
 
       - name: Init opam