Update Windows_MinGW_x64.yml

Author: wkdgmr

.github/workflows/Windows_MinGW_x64.yml

@@ -12,6 +12,7 @@ on:
     paths-ignore:
       - '*.md'
       - 'docs/**'
+  workflow_dispatch:
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}