feat(ci): Add check and update workflows

.forgejo/workflows/check.yml

@@ -0,0 +1,37 @@
+name: Perform checks
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  formatting:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install nix
+        uses: https://github.com/DeterminateSystems/nix-installer-action@main
+      - name: Setup Action cache for nix
+        uses: https://github.com/DeterminateSystems/magic-nix-cache-action@main
+        with:
+          fail-mode: true
+      - name: Check Nix flake inputs
+        uses: https://github.com/DeterminateSystems/flake-checker-action@v4 # This action
+      - name: Run nix fmt
+        run: nix fmt -- --check .
+
+  nix_flake_check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install nix
+        uses: https://github.com/DeterminateSystems/nix-installer-action@main
+      - name: Setup Action cache for nix
+        uses: https://github.com/DeterminateSystems/magic-nix-cache-action@main
+        with:
+          fail-mode: true
+      - name: Check Nix flake inputs
+        uses: https://github.com/DeterminateSystems/flake-checker-action@v4 # This action
+      - name: Run nix flake check
+        run: nix flake check