Fix from #497 by @bysiber with added test and lint fixes.

ReadWriteLock._acquire_transaction_lock() crashes with ValueError when called with blocking=False and a non-default timeout.

Python's threading.Lock.acquire() raises ValueError: can't specify a timeout for a non-blocking call when both blocking=False and a timeout are provided. The current code only special-cases timeout == -1, so any other timeout value combined with blocking=False hits this error:

from filelock import ReadWriteLock

lock = ReadWriteLock("test.db")
lock.acquire_read(timeout=5, blocking=False)
# ValueError: can't specify a timeout for a non-blocking call

The fix handles blocking=False as a separate branch that never passes a timeout argument, since a timeout is meaningless for non-blocking acquisition anyway.