What does this PR do?

Increases the size limit of the event payload in the local checks. This prevents two issues:

• sys.getsizeof calculates the size of the payload in memory, which can be larger that the size of the payload in the network HTTP request. This means some payloads are incorrectly blocked by this check.
• some dedicated clusters have a higher max payload size. This library in its current format does not support such clusters.

This change is safe as the API already checks the size of events and returns an error if too large.

• If you have changed dependencies, ensure both requirements.txt and setup.py have been updated

CHANGELOG

• [CHANGED] the maximum event payload size permitted by this library has been increased. This change affects the library only: the Channels API still maintains a 10kb size limit and will return an error if the payload is too large.