Sbot

Metadata is now no longer loaded until just after the start button is pressed. Trying to access metadata (`Robot().metadata`, `Robot().zone` or `Robot().is_competition`) before the start button has been pressed will now result in a `MetadataNotReadyError`.

Updates j5 to v0.7.6, which pulls in:

* Improve error message produced when buzz requests are sent to the power board too quickly.

j5 has been updated to v0.7.5, having the following effects:

* The timeout on serial reads in the SB Arduino hardware backend has been increased to accommodate the fact that it may take up to 1 second for a response to an ultrasound command to be sent.
* The error message that typically occurs when trying to communicate with a servo board that has no 12V power has been improved for clarity.

* Change match duration from 180s to 120s to match Smallpeice 2019 rules.
* The exception for accessing a singular board property now occurs at the point of attribute access, not `Robot` initialisation.
* Auxiliary board groups are now public

- Update j5