Fix missing-final-newline linter error

Author: miikka

Misc/NEWS.d/next/Library/2019-04-25-21-11-37.bpo-36461.TO5YyP.rst

@@ -1,3 +1,3 @@
 Make the target time of :meth:`timeit.Timer.autorange` configurable
 and add ``--target-time`` option to the command-line interface of
-:mod:`timeit`:.
+:mod:`timeit`:.