ci: exclude vendored watcher/ from super-linter

All super-linter failures come from watcher/, a vendored copy of the
third-party wtr/watcher library. Exclude it so the lint job reflects
FrankenPHP's own code. The `^` anchor leaves .github/actions/watcher/
and internal/watcher/ linted.

Author: alexandre-daubois

.github/workflows/lint.yaml

@@ -30,6 +30,8 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           LINTER_RULES_PATH: /
           MARKDOWN_CONFIG_FILE: .markdown-lint.yaml
+          # watcher/ is a vendored copy of the third-party wtr/watcher library
+          FILTER_REGEX_EXCLUDE: ^watcher/
           VALIDATE_CPP: false
           VALIDATE_JSCPD: false
           VALIDATE_GO: false