ci: Fix workflow events (#80)

This was found by auditing workflows based on research published here:

https://github.com/joeyparrish/workflow-cheat-sheet

The research was prompted by a workflow bug in Shaka Streamer

.github/workflows/publish-demo.yaml

@@ -14,6 +14,10 @@ on:
         required: true
         type: string
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   build:
     name: Build

.github/workflows/release-please.yml

@@ -17,21 +17,28 @@ jobs:
 
       # The logic below handles npm publication.  Each step is conditional on a
       # release having been created by someone merging the release PR.
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
+        with:
+          ref: refs/tags/${{ steps.release.outputs.tag_name }}
         if: ${{ steps.release.outputs.release_created }}
+
       - uses: actions/setup-node@v1
         with:
           node-version: 12
           registry-url: 'https://registry.npmjs.org'
         if: ${{ steps.release.outputs.release_created }}
+
       - run: npm ci
         if: ${{ steps.release.outputs.release_created }}
+
       - run: npm publish
         env:
           NODE_AUTH_TOKEN: ${{secrets.NPM_TOKEN}}
         if: ${{ steps.release.outputs.release_created }}
+
       - run: npm pack
         if: ${{ steps.release.outputs.release_created }}
+
       - uses: svenstaro/upload-release-action@483c1e56f95e88835747b1c7c60581215016cbf2
         with:
           repo_token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/test.yaml

@@ -9,6 +9,10 @@ on:
         description: "The ref to build and test."
         required: False
 
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.number || inputs.ref }}
+  cancel-in-progress: true
+
 jobs:
   test:
     name: Test
@@ -17,7 +21,7 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v2
         with:
-          ref: ${{ github.event.inputs.ref || github.ref }}
+          ref: ${{ inputs.ref || github.ref }}
 
       - name: Test
         run: |