ci: fix build action

Author: ilyazub

.github/workflows/gem-push.yml

@@ -16,9 +16,9 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - name: Set up Ruby 2.6
-      uses: actions/setup-ruby@v1
+      uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 2.6.x
+        ruby-version: 2.6
         bundler-cache: true
 
     - name: Run tests