fix(ci): allow pull_request workflow to run in merge queues

Author: msfjarvis

.github/workflows/pull_request.yml

@@ -5,7 +5,7 @@ on:
 name: Check pull request
 
 concurrency:
-  group: ${{ github.head_ref }}
+  group: ${{ github.head_ref || github.ref_name }}
   cancel-in-progress: true
 
 env:
@@ -19,6 +19,7 @@ jobs:
         uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
 
       - name: Check if relevant files have changed
+        if: ${{ github.head_ref != '' }}
         uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7.0.1
         id: service-changed
         with:
@@ -28,7 +29,7 @@ jobs:
             return await script({github, context})
 
       - name: Fail if no files changed
-        if: "${{ steps.service-changed.outputs.result != 'true' }}"
+        if: "${{ steps.service-changed.outputs.result != 'true' || github.head_ref != '' }}"
         shell: bash
         run: exit 1