Update gem-push.yml

Author: hendrixfan

Diff for: .github/workflows/gem-push.yml

@@ -22,7 +22,7 @@ jobs:
     # uses: ruby/setup-ruby@v1
       uses: ruby/setup-ruby@55283cc23133118229fd3f97f9336ee23a179fcf # v1.146.0
       with:
-        ruby-version: 2.6.x
+        ruby-version: 2.6.0
 
     - name: Publish to GPR
       run: |