tweak module description grammar

Author: gruns

icecream/__version__.py

@@ -17,5 +17,5 @@
 __contact__ = '[email protected]'
 __url__ = 'https://github.com/gruns/icecream'
 __description__ = (
-    'Never use print() to debug again; inspect variables, expressions, and '
+    'Never use print() to debug again: inspect variables, expressions, and '
     'program execution with a single, simple function call.')