ci: update nix go vendor hash if needed for dependabot PRs

Author: water-sucks

.github/workflows/nix-dependabot-update-hash.yml

@@ -0,0 +1,48 @@
+name: Update Nix Package Hash On Dependabot PRs
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+    branches:
+      - main
+
+jobs:
+  nix-update:
+    if: github.actor == 'dependabot[bot]'
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: write
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+
+      - name: Run nix-update
+        run: |
+          nix run nixpkgs#nix-update -- --flake pangolin-newt --no-src --version skip
+
+      - name: Check for changes
+        id: changes
+        run: |
+          if git diff --quiet; then
+            echo "changed=false" >> "$GITHUB_OUTPUT"
+          else
+            echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Commit and push changes
+        if: steps.changes.outputs.changed == 'true'
+        run: |
+          git config user.name "dependabot[bot]"
+          git config user.email "dependabot[bot]@users.noreply.github.com"
+
+          git add .
+          git commit -m "chore(nix): fix hash for updated go dependencies"
+          git push