typo fix in setup.py

Installation fails with the following Traceback, due to a missing comma in `setup.py`.

```
    Traceback (most recent call last):
      File "<string>", line 17, in <module>
      File "/Users/brad/.virtualenvs/cypher-lexer/src/cypher-lexer/setup.py", line 12
        entry_points = { 'pygments.lexers' : '.cyp = cypher.CypherLexer' }
                   ^
    SyntaxError: invalid syntax
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):

  File "<string>", line 17, in <module>

  File "/Users/brad/.virtualenvs/cypher-lexer/src/cypher-lexer/setup.py", line 12

    entry_points = { 'pygments.lexers' : '.cyp = cypher.CypherLexer' }

               ^

SyntaxError: invalid syntax
```