Drop use of comprimised action

https://www.stepsecurity.io/blog/harden-runner-detection-tj-actions-changed-files-action-is-compromised

Author: tstellar

.github/workflows/pr-code-format.yml

@@ -11,36 +11,36 @@ on:
 
 jobs:
   code_formatter:
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-latest
     timeout-minutes: 30
     concurrency:
       group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
       cancel-in-progress: true
     if: github.repository == 'llvm/clangir'
     steps:
       - name: Fetch LLVM sources
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@v4
         with:
           ref: ${{ github.event.pull_request.head.sha }}
 
       - name: Checkout through merge base
-        uses: rmacklin/fetch-through-merge-base@bfe4d03a86f9afa52bc1a70e9814fc92a07f7b75 # v0.3.0
+        uses: rmacklin/fetch-through-merge-base@v0
         with:
           base_ref: ${{ github.event.pull_request.base.ref }}
           head_ref: ${{ github.event.pull_request.head.sha }}
           deepen_length: 500
 
       - name: Get changed files
         id: changed-files
-        uses: step-security/changed-files@3dbe17c78367e7d60f00d78ae6781a35be47b4a1 # v45.0.1
+        uses: step-security/changed-files@3dbe17c78367e7d60f00d78ae6781a35be47b4a1
         with:
           separator: ","
           skip_initial_fetch: true
 
       # We need to pull the script from the main branch, so that we ensure
       # we get the latest version of this script.
       - name: Fetch code formatting utils
-        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        uses: actions/checkout@v4
         with:
           repository: ${{ github.repository }}
           ref: ${{ github.base_ref }}
@@ -58,12 +58,12 @@ jobs:
           echo "$CHANGED_FILES"
 
       - name: Install clang-format
-        uses: aminya/setup-cpp@17c11551771948abc5752bbf3183482567c7caf0 # v1.1.1
+        uses: aminya/setup-cpp@v1
         with:
           clangformat: 19.1.6
 
       - name: Setup Python env
-        uses: actions/setup-python@42375524e23c412d93fb67b49958b491fce71c38 # v5.4.0
+        uses: actions/setup-python@v5
         with:
           python-version: '3.11'
           cache: 'pip'