Merge #6253: ci: fix, in github actions CI actually check out the PR

fb92a8e ci: fix, in github actions CI, we don't actually check out the PR, but the base (pasta)

Pull request description:

  ## Issue being fixed or feature implemented
  Actually check out the PR for GitHub actions CI. I knew this was an issue for a lil bit since we implemented it. Time to fix it.

  Note: Github Actions based CI is experimental, and we still primarily use GitLab. Functionals tests don't even run on GitHub Actions CI yet.

  ## What was done?
  Check out the actual PR commit

  ## How Has This Been Tested?

  ## Breaking Changes
  None

  ## Checklist:
  - [ ] I have performed a self-review of my own code
  - [ ] I have commented my code, particularly in hard-to-understand areas
  - [ ] I have added or updated relevant unit/integration/functional/e2e tests
  - [ ] I have made corresponding changes to the documentation
  - [x] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

ACKs for top commit:
  UdjinM6:
    utACK fb92a8e

Tree-SHA512: 31b3737328ac66217c66c99efce6a3ccfe9e8b9a2453a8b226c12c394e2433828d20165a9dfa4c9463ae4fa5015a7d07f451dde98e937a230e04087383230a02

.github/workflows/build.yml

@@ -22,6 +22,9 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+
 
       - name: Prepare
         id: prepare
@@ -84,6 +87,9 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+
 
       - name: Cache dependencies
         uses: actions/cache@v4
@@ -132,6 +138,9 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
+
 
       - name: Restore Cache dependencies
         uses: actions/cache/restore@v4
@@ -190,6 +199,8 @@ jobs:
 #    steps:
 #      - name: Checkout code
 #        uses: actions/checkout@v4
+#        with:
+#          ref: ${{ github.event.pull_request.head.sha }}
 #
 #      - name: Download build artifacts
 #        uses: actions/download-artifact@v4