Run merge request pipelines for pre-commit.

Link: https://docs.gitlab.com/ee/ci/pipelines/merge_request_pipelines.html#use-rules-to-add-jobs
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

.gitlab-ci.yml

@@ -9,6 +9,10 @@ check-commits:
 pre-commit:
   stage: test
   image: registry.gitlab.com/kernel-firmware/linux-firmware
+  rules:
+    - if: $CI_PIPELINE_SOURCE == 'merge_request_event'
+    - if: $CI_COMMIT_TAG
+    - if: $CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH
   script:
     - pre-commit run --all-files