CI: Add concurrency control snippets where they have been missing

Author: amotl

.github/workflows/release-app.yml

@@ -9,6 +9,11 @@ on:
     tags:
       - '*'
 
+# Cancel in-progress jobs when pushing to the same branch.
+concurrency:
+  cancel-in-progress: true
+  group: ${{ github.workflow }}-${{ github.ref }}
+
 jobs:
 
   cfr:

.github/workflows/release-pypi.yml

@@ -6,6 +6,11 @@ on:
     tags:
       - '*.*.*'
 
+# Cancel in-progress jobs when pushing to the same branch.
+concurrency:
+  cancel-in-progress: true
+  group: ${{ github.workflow }}-${{ github.ref }}
+
 jobs:
   build-and-publish:
     name: Build & publish package to PyPI