Cancel previous CI runs automatically. (#209)

Author: tobiasraabe

.github/workflows/continuous-integration-workflow.yml

@@ -1,5 +1,10 @@
 name: Continuous Integration Workflow
 
+# Automatically cancel a previous run.
+concurrency:
+  group: ${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
 on:
   push:
     branches:

docs/source/changes.rst

@@ -24,6 +24,7 @@ all releases are available on `PyPI <https://pypi.org/project/pytask>`_ and
 - :gh:`204` removes internal traceback frames from exceptions raised somewhere in
   pytask.
 - :gh:`208` fixes the best practices guide for parametrizations.
+- :gh:`209` cancels previous CI runs automatically.
 
 
 0.1.5 - 2022-01-10