ci: pin editorconfig checker to a compatible release

The setup action searches for ec-prefixed release assets, which editorconfig-checker v4.0.0 no longer publishes. Pin v3.11.2 so the existing installer can run the formatting check.

Author: bvolpato

.github/workflows/pr.yml

@@ -16,6 +16,8 @@ jobs:
         with:
           fetch-depth: 0
       - uses: editorconfig-checker/action-editorconfig-checker@v2.2.0
+        with:
+          version: v3.11.2
       - run: editorconfig-checker
   yamllint:
     name: Lint YAML