fix(pre-commit): Don't require serial execution

require_serial is not pertinent to commit-msg hooks or hooks that
themselves execute serially. The option is intended to prevent
fork-bombing that can occur when pre-commit runs a hook that itself
spawns many processes many times in parallel.

Author: Kurt-von-Laven

.pre-commit-hooks.yaml

@@ -4,5 +4,4 @@
   entry: cz check --commit-msg-file
   language: python
   language_version: python3
-  require_serial: true
   minimum_pre_commit_version: "0.15.4"