add trailing whitespace hook (#44474)

.pre-commit-config.yaml

@@ -25,6 +25,8 @@ repos:
     -   id: end-of-file-fixer
     -   id: sort-simple-yaml
         files: (api|backward|api_[a-z_]+)\.yaml$
+    -   id: trailing-whitespace
+        files: (.*\.(py|bzl)|BUILD|.*\.BUILD|WORKSPACE)$
 -   repo: local
     hooks:
     -   id: clang-format