implement wildcards

[Vizonex]

while attempting to use this library on numerous files in order to modernize older libraries I bumped into a problem were multiple needed to be traversed so I came up with a cleaver idea to help eliminate some problems by implementing wildcards. Now on Linux this may work without what I have added in but in Windows this does matter. So hopefully this addition will prove useful in the long run. Here's an example that I have tested with this new additional feature such as upgrading h11's 3.8 code on over to 3.9 which writing all of these files down can be extremely annoying...

> pyupgrade h11/*.py --py39-plus

Rewriting h11\_connection.py
Rewriting h11\_events.py
Rewriting h11\_headers.py
Rewriting h11\_readers.py
Rewriting h11\_receivebuffer.py
Rewriting h11\_state.py
Rewriting h11\_util.py
Rewriting h11\_writers.py

[asottile]

search the issue tracker next time, thanks!