Cancel running workflows before starting new ones (#13)

Cancel running tests before starting new ones
Fixes #12

Co-authored-by: tyler36 <[email protected]>

Author: tyler36

Diff for: .github/workflows/tests.yml

@@ -14,6 +14,10 @@ on:
         required: false
         default: "false"
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 # required for keep-alive workflow.
 permissions:
   actions: write