Cancel previous workflows on update

Author: chrismallinson

.github/workflows/update-seed.yml

@@ -19,7 +19,10 @@ on:
       - main
   workflow_dispatch:
 
-# CHRISM - look at concurrency setup and replicate here
+# Cancel previous workflows on previous push
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
 
 permissions:
   pull-requests: write