chore(ci): Add CI job to update flake dependencies

.github/workflows/update-flake.yml

@@ -0,0 +1,22 @@
+name: Update flake dependencies
+
+on:
+  schedule:
+    - cron: '0 16 * * 5'
+  workflow_dispatch: # for allowing manual triggers of the workflow
+
+jobs:
+  update-dependencies:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: DeterminateSystems/nix-installer-action@main
+    - uses: DeterminateSystems/magic-nix-cache-action@main
+    - name: update flake.lock
+      run: nix flake update
+    - name: Create Pull Request
+      uses: peter-evans/create-pull-request@v6
+      with:
+        commit-message: "flake: update dependencies"
+        title: "[automation] update flake dependencies"
+        branch: "automation/update-flake-dependencies"