ci: add release-please workflow

Release please automates changelog and release notes generation for conventional commits.

.github/workflows/release.yml

@@ -0,0 +1,18 @@
+name: release
+
+on:
+  push:
+    branches: [main]
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  release-please:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: google-github-actions/release-please-action@v3
+        with:
+          release-type: simple
+          package-name: catppuccin/nix