ci: test nix flake checks action

.forgejo/workflows/check.yml

@@ -1,19 +1,12 @@
-name: Gitea Actions Demo
-run-name: ${{ gitea.actor }} is testing out Gitea Actions 🚀
+name: Flake checks
 on: [push]
 
 jobs:
-  Explore-Gitea-Actions:
-    runs-on: ubuntu-latest
+  Check:
+    runs-on: nix-flakes
     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: https://code.forgejo.org/actions/checkout@v4
-      - 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
+      - name: Run flake checks
         run: |
-          ls ${{ gitea.workspace }}
-      - run: echo "🍏 This job's status is ${{ job.status }}."
+          nix --print-build-logs --verbose --accept-flake-config flake check