Add a demo action

(see https://blog.gitea.io/2023/03/hacking-on-gitea-actions/)

.gitea/workflows/demo.yaml

@@ -0,0 +1,18 @@
+name: Gitea Actions Demo
+run-name: ${{ gitea.actor }} is testing out Gitea Actions 🚀
+on: [push]
+jobs:
+  Explore-Gitea-Actions:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo "🎉 The job was automatically triggered by a ${{ gitea.event_name }} event."
+      - run: echo "🐧 This job is now running on a ${{ runner.os }} server hosted by Gitea!"
+      - run: echo "🔎 The name of your branch is ${{ gitea.ref }} and your repository is ${{ gitea.repository }}."
+      - name: Check out repository code
+        uses: actions/checkout@v3
+      - run: echo "💡 The ${{ gitea.repository }} repository has been cloned to the runner."
+      - run: echo "🖥️ The workflow is now ready to test your code on the runner."
+      - name: List files in the repository
+        run: |
+          ls ${{ gitea.workspace }}          
+      - run: echo "🍏 This job's status is ${{ gitea.status }}."