Add concurrency cancellation for test/build GitHub Actions (#2710)

The GitHub Actions build queue can get 'stacked up' if there are a few smaller commits in quick succession. Since the actions take some time, some small commits can cause the GHA build queue to get congested.

This adds a 'concurrency' check for GitHub actions. It means that if a newer trigger comes in (for example, if you make two commits in a row on a PR), then the first job will be cancelled, allowing for the new job to run.

This helps save energy, and for faster feedback in PRs.

Reference docs: https://docs.github.com/en/actions/using-jobs/using-concurrency#example-using-concurrency-to-cancel-any-in-progress-job-or-run

.github/workflows/check.yml

@@ -2,6 +2,10 @@ name: Check
 
 on: pull_request
 
+concurrency:
+  group: '${{ github.workflow }} @ ${{ github.event.pull_request.head.label || github.head_ref || github.ref }}'
+  cancel-in-progress: true
+
 jobs:
   validate-wrapper:
     runs-on: ubuntu-latest

.github/workflows/dokka-examples.yml

@@ -2,6 +2,10 @@ name: Build examples
 
 on: pull_request
 
+concurrency:
+  group: '${{ github.workflow }} @ ${{ github.event.pull_request.head.label || github.head_ref || github.ref }}'
+  cancel-in-progress: true
+
 jobs:
   build:
     strategy:

.github/workflows/gradle-test.pr.yml

@@ -2,6 +2,10 @@ name: Test
 
 on: pull_request
 
+concurrency:
+  group: '${{ github.workflow }} @ ${{ github.event.pull_request.head.label || github.head_ref || github.ref }}'
+  cancel-in-progress: true
+
 jobs:
   test-ubuntu:
     strategy:

.github/workflows/qodana.yml

@@ -7,6 +7,10 @@ on:
     branches:
       - master
 
+concurrency:
+  group: '${{ github.workflow }} @ ${{ github.event.pull_request.head.label || github.head_ref || github.ref }}'
+  cancel-in-progress: true
+
 jobs:
   inspection:
     runs-on: ubuntu-latest