ci(workflows): [ci] fix gitguardian env

- https://github.com/GitGuardian/ggshield-action/blob/v1.34.0/.github/workflows/main.yml

Signed-off-by: Lexus Drumgold <[email protected]>

Author: unicornware

.github/workflows/ci.yml

@@ -155,7 +155,7 @@ jobs:
           GITGUARDIAN_API_KEY: ${{ secrets.GITGUARDIAN_API_KEY }}
           GITHUB_DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
           GITHUB_PULL_BASE_SHA: ${{ github.event.pull_request.base.sha }}
-          GITHUB_PUSH_BASE_SHA: ${{ env.SHA }}
+          GITHUB_PUSH_BASE_SHA: ${{ github.event.base }}
           GITHUB_PUSH_BEFORE_SHA: ${{ github.event.before }}
         with:
           args: --all-policies --ignore-known-secrets --show-secrets --verbose