Update calendar to include bi-weekly Zarr-python refactor standup

[jhamman]

We have decided to have a 30 minute bi-weekly standup meeting to track progress on the Zarr-python refactor working group (zarr-developers/zarr-python#1480).

This meeting is scheduled for 9a PT. The first meeting should be set for September 6th, 2023 and repeated every 2 weeks until the end of 2023.

@MSanKeys963 - do you need additional information to make this happen?

[sanketverma1704]

Thanks for the kick-off meeting, @jhamman.
I've added the bi-weekly standup meeting to the Zarr Community Calendar starting 09/06.

Please see here: https://zarr.dev/community-calls/.