Fix U+2019 (RIGHT SINGLE QUOTATION MARK) used instead of "'" in Python code. (#237)

pep-0526.txt

@@ -278,7 +278,7 @@ As a matter of convenience (and convention), instance variables can be
 annotated in ``__init__`` or other methods, rather than in the class::
 
   from typing import Generic, TypeVar
-  T = TypeVar(’T’)
+  T = TypeVar('T')
 
   class Box(Generic[T]):
       def __init__(self, content):