Added pre-commit config

.github/workflows/test.yml

@@ -20,6 +20,8 @@ jobs:
       - name: Calculate build matrix
         id: set-matrix
         run: |
+          # Use `-c` flag with jq for compact output (doesn't keep newlines in
+          # output which was causing issues when setting the output
           matrix=$(nix flake show --json | jq -c '.nixosConfigurations | keys')
           echo "::set-output name=matrix::$matrix"
 

.pre-commit-config.yaml

@@ -0,0 +1,12 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.3.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-added-large-files
+  - repo: https://github.com/kamadorueda/alejandra
+    rev: 3.0.0
+    hooks:
+      - id: alejandra-system