fix: WindowsError keyword is undefined on non-Windows platforms (#117)

WindowsError is a subclass of `OSError`. It is defined and raised only
in Windows. Hence the exception statement will return a
`WindowsError keyword is undefined` in other platforms.

Usually this error is encountered when CodeUri: /folder/does/not/exist. The builder tries to copy the files and fails because the path does not exist. On Windows, the exception handler works, but on Mac/Linux Python interpreter does not find the variable WindowsError and crashes. So it leads to a vague WindowsError on Mac/Linux.

aws_lambda_builders/utils.py

@@ -36,7 +36,7 @@ def copytree(source, destination, ignore=None):
         try:
             # Let's try to copy the directory metadata from source to destination
             shutil.copystat(source, destination)
-        except WindowsError as ex:  # pylint: disable=undefined-variable
+        except OSError as ex:
             # Can't copy file access times in Windows
             LOG.debug("Unable to copy file access times from %s to %s", source, destination, exc_info=ex)