Update peter-evans/create-pull-request action to v8

Author: renovate[bot]

.github/workflows/openapi-generate.yml

@@ -18,7 +18,7 @@ jobs:
     - name: OpenAPI Generate
       run: bin/openapi-generate
     - name: Create Pull Request
-      uses: peter-evans/create-pull-request@v7
+      uses: peter-evans/create-pull-request@v8
       with:
         add-paths: |
           .openapi-generator