chore: bump GitGuardian/ggshield-action from 1.19.1 to 1.20.0 (#64)

Bumps [GitGuardian/ggshield-action](https://github.com/gitguardian/ggshield-action) from 1.19.1 to 1.20.0.
- [Release notes](https://github.com/gitguardian/ggshield-action/releases)
- [Commits](GitGuardian/ggshield-action@31037b4...4848e49)

---
updated-dependencies:
- dependency-name: GitGuardian/ggshield-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/git-guardian.yml

@@ -18,7 +18,7 @@ jobs:
         with:
           fetch-depth: 0 # fetch all history so multiple commits can be scanned
       - name: GitGuardian scan
-        uses: GitGuardian/ggshield-action@31037b4c0084321265050375fc799278393fb836 # v1.19.1
+        uses: GitGuardian/ggshield-action@4848e499be8c740d2d71526182c1343d577d7322 # v1.20.0
         env:
           GITHUB_PUSH_BEFORE_SHA: ${{ github.event.before }}
           GITHUB_PUSH_BASE_SHA: ${{ github.event.base }}