ci: move github workflows to gitea

.gitea/workflows/update.yml

@@ -0,0 +1,24 @@
+name: "Update flake inputs"
+on:
+  workflow_dispatch:
+  schedule:
+    # bump weekly at 6:50
+    - cron:  '50 6 * * 1'
+jobs:
+  update-flake:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v23
+        with:
+          extra_nix_config: |
+            access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
+      - name: "flake: update inputs"
+        uses: DeterminateSystems/update-flake-lock@v20
+        with:
+          pr-title: "flake: update inputs"
+          pr-labels: dependencies
+          commit-msg: "flake: update inputs"