fix gem push error

Author: anoworl

.github/workflows/release.yml

@@ -17,9 +17,9 @@ jobs:
       - id: gem
         run: echo "::set-output name=result::$(find pkg -name 'deploygate-*.gem' -type f | head -1)"
       - run: |
-          curl --data-binary '@${{ steps.gem.outputs.result }}' \
-            -H 'Authorization: ${{ secrets.RUBYGEMS_API_KEY }}' \
-            "https://rubygems.org/api/v1/gems"
+          gem push '${{ steps.gem.outputs.result }}'
+        env:
+          GEM_HOST_API_KEY: ${{ secrets.RUBYGEMS_API_KEY }}
       - uses: slackapi/slack-github-action@v1.16.0
         with:
           payload: "{\"text\": \"Released a deploygate gem in <https://rubygems.org/gems/deploygate/|RubyGems>\"}"