Adds a pre-commit hook for ggshield not in a CI environment

Author: iainsproat

.pre-commit-hooks.yaml

@@ -0,0 +1,6 @@
+- id: ggshield-not-ci
+  name: GitGuardian Shield (pre-commit)
+  entry: bash -c 'if [[ ! -z ${CI}} ]]; then ggshield secret scan pre-commit; fi'
+  description: Runs ggshield in non-CI environments to detect hardcoded secrets, security vulnerabilities and policy breaks.
+  stages: [commit]
+  language: system