ci: update workflow to use swagger-cli for OpenAPI validation

Author: Valentin Schneider-Lunitz

.github/workflows/ci.yml

@@ -1,7 +1,9 @@
 name: Lint and validate OpenAPI specs
+
 on:
   - push
   - pull_request_target
+
 jobs:
   lint:
     name: Lint OpenAPI definition
@@ -14,6 +16,7 @@ jobs:
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           file: openapi/workflow_execution_service.openapi.yaml
+
   diff:
     name: Show OpenAPI differences relative to target branch
     runs-on: ubuntu-latest
@@ -41,7 +44,10 @@ jobs:
     steps:
       - name: Check out head branch
         uses: actions/checkout@v3
-      - name: Run OpenAPI Validate Action
-        uses: char0n/swagger-editor-validate@v1
-        with:
-          definition-file: openapi/workflow_execution_service.openapi.yaml
+
+      # Replace Puppeteer-based validation with swagger-cli
+      - name: Install swagger-cli
+        run: npm install -g @apidevtools/swagger-cli
+
+      - name: Validate OpenAPI definition
+        run: swagger-cli validate openapi/workflow_execution_service.openapi.yaml