stop using deprecated logger.warn

Author: rotu

colcon_core/package_identification/python.py

@@ -79,7 +79,7 @@ def get_setup_result(setup_py, env=None):
     p.start()
     p.join()
     if p.exitcode:
-        logger.warn("Python setup script '%s' terminated with exit code %d",
+        logger.warning("Python setup script '%s' terminated with exit code %d",
                     setup_py, p.exitcode)
 
     if not conn_recv.poll():