Run check fmt in python project

Author: w1th0utnam3

.github/workflows/pysplashsurf_CI.yml

@@ -15,6 +15,14 @@ permissions:
   contents: read
 
 jobs:
+  check_format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Check formatting of PySplashsurf
+        run: cargo fmt -- --check
+        working-directory: pysplashsurf
+
   generate-stub:
     runs-on: ubuntu-latest
     steps: