NFC: fix typo in build_swift/versions.py

Author: MaxDesiatov

utils/build_swift/build_swift/versions.py

@@ -168,7 +168,7 @@ def __init__(self, version, msg=None):
 
 @functools.total_ordering
 class Version(object):
-    """Similar to the standard distutils.versons.LooseVersion, but with a
+    """Similar to the standard distutils.version.LooseVersion, but with a
     little more wiggle-room for alpha characters.
     """