NFC: fix typo in versions.py

boundries -> boundaries

Author: Ikko Ashimine

utils/build_swift/build_swift/versions.py

@@ -95,7 +95,7 @@ def _try_cast(obj, cls):
 def _split_version(version):
     """Splits a version string into a tuple of components using similar rules
     to distutils.version.LooseVersion. All version strings are valid, but the
-    outcome will only split on boundries between:
+    outcome will only split on boundaries between:
 
         * lowercase alpha characters
         * uppercase alpha characters