ci: add format checking job

Signed-off-by: Patrizio Bekerle <[email protected]>

Author: pbek

.github/workflows/format-check.yml

@@ -0,0 +1,21 @@
+name: 📄 Check formatting
+
+on:
+    push:
+        branches-ignore:
+            - release
+        tags-ignore:
+            - "*"
+    pull_request:
+    workflow_dispatch:
+
+jobs:
+    format-check:
+        name: 📄 Check code formatting with "just fmt"
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v4
+            - uses: cachix/install-nix-action@v31
+              with:
+                  nix_path: nixpkgs=channel:nixos-unstable
+            - run: nix-shell -p just --run "just fmt --ci"