Build/Test Tools: Update actions within test workflows to the latest versions.

This updates two published GitHub actions to their latest versions:

- `actions/setup-node` from `v1` to `v2`.
- `styfle/cancel-workflow-action` from `0.5.0` to `0.8.0`.

See #50401.

git-svn-id: https://develop.svn.wordpress.org/trunk@50387 602fd350-edb4-49c9-b593-d223f7449a82

.github/workflows/javascript-tests.yml

@@ -33,7 +33,7 @@ jobs:
     steps:
       - name: Cancel previous runs of this workflow (pull requests only)
         if: ${{ github.event_name == 'pull_request' }}
-        uses: styfle/cancel-workflow-action@0.5.0
+        uses: styfle/cancel-workflow-action@0.8.0
         with:
           access_token: ${{ github.token }}
 
@@ -48,7 +48,7 @@ jobs:
           svn --version
 
       - name: Install NodeJS
-        uses: actions/setup-node@v1
+        uses: actions/setup-node@v2
         with:
           node-version: 14