[CI] Require D*-audit labels for any runtime changes (#8345)

* add check for audit labels if runtime change

* fix shellcheck nits

* include lib.sh in check_runtime.sh

* fix check_labels.sh

* fix check_labels.sh

* oops, this is github actions...

* why wont this work

* fetch all refs

* Update check-labels.yml

* print env - wtf is happening

* checkout the PR...

* ffs

* fix

* REVERT ME: test runtime check

* Revert "REVERT ME: test runtime check"

This reverts commit 0fd2b04abeeac12dd8ede4c0708cb796f9e3e722.

substrate/.github/workflows/check-labels.yml

@@ -9,8 +9,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.ref }}
       - name: Check labels
         run: bash ${{ github.workspace }}/.maintain/github/check_labels.sh
         env:
           GITHUB_PR: ${{ github.event.pull_request.number }}
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          HEAD_SHA: ${{ github.event.pull_request.head.sha }}