Revert "CI: cancel other builds if others are building for the same commit too (this happens when a commit is tagged)" as it causes the CI to look like it has failed when it hasn't

This reverts commit 60fe40e509.

.github/workflows/CI.yml

@@ -10,9 +10,6 @@ on:
 jobs:
   CI:
     runs-on: ubuntu-latest
-    concurrency:
-      group: ${{ github.sha }}
-      cancel-in-progress: true
     steps:
     - name: Checkout
       uses: actions/checkout@v3