unpin docker version in pre-commit hook (#832)

eliminating inconsistency. e.g. for version 8.6.1, pre-commit hooks points to outdated version https://github.com/zricethezav/gitleaks/blob/c33ee3f25215635c0afbb210672779e7efb6f1d2/.pre-commit-hooks.yaml#L10

.pre-commit-hooks.yaml

@@ -7,5 +7,5 @@
 - id: gitleaks-docker
   name: Detect hardcoded secrets
   description: Detect hardcoded secrets using Gitleaks
-  entry: zricethezav/gitleaks:v8.5.2 protect --verbose --redact --staged
+  entry: zricethezav/gitleaks protect --verbose --redact --staged
   language: docker_image