Notify Slack when GHA Runs (#396)

* Notify Slack when GHA Runs

* Only notify in case of failure

.github/workflows/ci.yml

@@ -27,6 +27,13 @@ jobs:
           - "3.1"
           - "3.0"
     steps:
+      - uses: ravsamhq/notify-slack-action@v1
+        if: always()
+        with:
+          status: ${{ job.status }}
+          notify_when: "failure"
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}
       - uses: actions/checkout@v1
       - name: Install package dependencies
         run: "[ -e $APT_DEPS ] || sudo apt-get install -y --no-install-recommends $APT_DEPS"