gitea-actions-runner: fix env variable

.forgejo/workflows/nightly-update.yaml

@@ -1,21 +1,22 @@
-on:
-  push:
-    branches:
-      - main
+on: 
   schedule:
     - cron: 0 */6 * * *
   
 jobs:
-  updateflake:
+  UpdateFlake:
     runs-on: native
+
     steps:
       - name: Check out repository code
         uses: actions/checkout@v4
-      - run: | 
+      - name: Update flake
+        run: | 
           cd ${{ env.FORGEJO_WORKSPACE }}
           nix flake update
-      - run: |
+      - name: Commit new Flake.lock
+        run: |
           git config --local user.email "christoph.hollizeck@hey.com"
           git config --local user.name "forgjo-actions[bot]"
           git commit -a -m "chore: update flake"
-      - run: git push
+      - name: Push changes
+        run: git push