port to flakes

.github/workflows/nix-flake-update.yml

@@ -0,0 +1,38 @@
+name: "Update flakes"
+on:
+  repository_dispatch:
+  workflow_dispatch:
+  schedule:
+    - cron:  '10 4 * * 0'
+jobs:
+  createPullRequest:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: cachix/install-nix-action@v13
+        with:
+          install_url: https://github.com/numtide/nix-flakes-installer/releases/download/nix-2.4pre20210604_8e6ee1b/install
+          extra_nix_config: |
+            experimental-features = nix-command flakes
+      - name: Make changes to pull request
+        run: nix flake update
+      - name: Create Pull Request
+        id: cpr
+        uses: peter-evans/create-pull-request@v3
+        with:
+          commit-message: Update flakes
+          committer: GitHub <noreply@github.com>
+          author: ${{ github.actor }} <${{ github.actor }}@users.noreply.github.com>
+          signoff: false
+          branch: flake-updates
+          delete-branch: true
+          title: 'Update flakes'
+          body: |
+            Update report
+            - Updated with *today's* date
+            - Auto-generated by [create-pull-request][1]
+            [1]: https://github.com/peter-evans/create-pull-request
+      - name: Check outputs
+        run: |
+          echo "Pull Request Number - ${{ steps.cpr.outputs.pull-request-number }}"
+          echo "Pull Request URL - ${{ steps.cpr.outputs.pull-request-url }}"