Merge pull request #12258 from tschaub/codeql-update

Following the recommendation to run on a merge commit

.github/workflows/security.yml

@@ -23,12 +23,6 @@ jobs:
           # Only include this option if you are running this workflow on pull requests.
           fetch-depth: 2
 
-      # If this run was triggered by a pull request event then checkout
-      # the head of the pull request instead of the merge commit.
-      # Only include this step if you are running this workflow on pull requests.
-      - run: git checkout HEAD^2
-        if: ${{ github.event_name == 'pull_request' }}
-
       # Initializes the CodeQL tools for scanning.
       - name: Initialize CodeQL
         uses: github/codeql-action/init@v1