fix: update OpenAPI Validate Action to version 1.5.1

Author: Valentin Schneider-Lunitz

.github/workflows/ci.yml

@@ -42,6 +42,6 @@ jobs:
       - name: Check out head branch
         uses: actions/checkout@v4
       - name: Run OpenAPI Validate Action
-        uses: swaggerexpert/swagger-editor-validate@v1
+        uses: swaggerexpert/swagger-editor-validate@v1.5.1
         with:
           definition-file: openapi/workflow_execution_service.openapi.yaml