fix format issue

Author: rajkan01

src/mbed_tools/build/config.py

@@ -41,6 +41,7 @@ def generate_config(target_name: str, toolchain: str, program: MbedProgram) -> p
  write_file(cmake_config_file_path, cmake_file_contents)
  return cmake_config_file_path
 
+
 def is_image_hex(target_name: str, program: MbedProgram) -> bool:
  """Check if a target's image format is hex instead of bin.
 
@@ -55,6 +56,7 @@ def is_image_hex(target_name: str, program: MbedProgram) -> bool:
  target_build_attributes = get_target_by_name(target_name, targets_data)
  return "OUTPUT_EXT" in target_build_attributes and target_build_attributes["OUTPUT_EXT"] == "hex"
 
+
 def _load_raw_targets_data(program: MbedProgram) -> Any:
  targets_data = decode_json_file(program.mbed_os.targets_json_file)
  if program.files.custom_targets_json.exists():