CI: Modernize examples test script

- Rename workflow
- Run on each push (which allows developing on test branches in this repo)
- Run only on changes to the example models, the test script or the CI config
- Allow multiple commits after each other (to allow continuous trial and error

.github/workflows/build_lint.yml → .github/workflows/test_examples.yml

@@ -1,28 +1,20 @@
-name: build
+name: Test example models
 
 on:
   push:
-    branches:
-    - main
-    - release**
-    paths-ignore:
-      - '**.md'
-      - '**.rst'
+    paths:
+      - 'examples/**/*.py'  # If an example model is modified
+      - 'test_examples.py'  # If the test script is modified
+      - '.github/workflows/test_examples.yml'  # If this workflow is modified
   pull_request:
-    paths-ignore:
-      - '**.md'
-      - '**.rst'
+    paths:
+      - 'examples/**/*.py'
+      - 'test_examples.py'
+      - '.github/workflows/test_examples.yml'
   workflow_dispatch:
   schedule:
     - cron: '0 6 * * 1'  # Monday at 6:00 UTC
 
-# This will cancel previous run if a newer job that obsoletes the said previous
-# run, is started.
-# Based on https://github.com/zulip/zulip/commit/4a11642cee3c8aec976d305d51a86e60e5d70522
-concurrency:
-  group: "${{ github.workflow }}-${{ github.head_ref || github.run_id }}"
-  cancel-in-progress: true
-
 jobs:
   # build-stable:
   #   runs-on: ubuntu-latest