If datashader is unable to startup if there are too many cache files

[desean1625]

gunicorn times out the worker while it tries to clear the cache because it takes too long to glob the files in the cache directory.

https://docs.gunicorn.org/en/stable/settings.html#timeout

Potential temporary relief to increase the timeout time. but need a long term solution.

[desean1625]

fixed in 5f3650f