Don't format files in the SwiftPM build directory

Otherwise, we might try to format files in `CodeGeneration/.build`

Author: ahoppen

format.py

@@ -99,6 +99,8 @@ def should_exclude(path: Path) -> bool:
             return True
         elif 'Inputs' in path.parts:
             return True
+        elif '.build' in path.parts:
+            return True
         return False
 
     files_to_format = [file for file in files_to_format if not should_exclude(file)]