ci/eval: cancel previous run if new code is pushed

<!-- ps-id: 4f58e709-5f02-4915-8af4-d320e8a7748e -->

Author: Mic92

.github/workflows/eval.yml

@@ -13,6 +13,11 @@ on:
       - haskell-updates
       - python-updates
 
+# Cancel previous if someone pushed an update
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
 permissions: {}
 
 jobs: