check code formatting in CI

Author: Techatrix

.github/workflows/build.yml

@@ -27,6 +27,10 @@ jobs:
         with:
           version: master
 
+      - name: Run zig fmt
+        if: matrix.os == 'ubuntu-latest'
+        run: zig fmt --check .
+
       - name: Run Tests
         run: zig build test --summary all