Add import for TextLexer. (#5512)
Add import for TextLexer. (#5512)

If pygments did not recognize the language name it was being passed,
this would raise a `NameError` because `TextLexer` import was missing.
jpadilla/django-rest-framework,tomchristie/django-rest-framework,tomchristie/django-rest-framework,jpadilla/django-rest-framework,jpadilla/django-rest-framework,kgeorgy/django-rest-framework,tomchristie/django-rest-framework,kgeorgy/django-rest-framework,kgeorgy/django-rest-framework