CI: do not cancel concurrent builds on the same branch

Instead, only cancel them if the builds have the same commit SHA.

Author: Kobzol

.github/workflows/ci.yml

@@ -31,7 +31,7 @@ defaults:
   run:
     shell: bash
 concurrency:
-  group: "${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}"
+  group: "${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}"
   cancel-in-progress: true
 jobs:
   pr:

src/ci/github-actions/ci.yml

@@ -301,7 +301,7 @@ defaults:
 concurrency:
   # For a given workflow, if we push to the same PR, cancel all previous builds on that PR.
   # If the push is not attached to a PR, we will cancel all builds related to the same commit SHA.
-  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.sha }}
   cancel-in-progress: true
 
 jobs: