Update publish-gem.yml

Author: arcwhite

.github/workflows/publish-gem.yml

@@ -14,7 +14,7 @@ jobs:
       - name: Set up Ruby 3.1
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '3.1.x'
+          ruby-version: '3.1.0'
       - name: Publish to GPR
         run: |
           mkdir -p $HOME/.gem