chore: setup pre-commit (bazel-contrib#181)

otherwise I keep wasting time on red PRs that fail on the prettier-check
step

Author: alexeagle

.pre-commit-config.yaml

@@ -0,0 +1,8 @@
+# https://pre-commit.com/
+# Runs prettier on changed files as part of git commit
+
+repos:
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    rev: v3.0.0
+    hooks:
+      - id: prettier