convert gsp_ids="" to None

[peterdudfield]

Pull Request

Description

Small change for converting gsp_ids

1. Do it at the start of the route
2. if "" then set to None

I tried using Annoted and AfterValidator but couldnt seem to get it working, I'm happy to try again if you prefer

Helps with https://github.com/openclimatefix/client-private/issues/337
(it wont fix this bug, as only the start time is set, but this might be something that needs to be fixed in the UI)

How Has This Been Tested?

• CI tests

Checklist:

• My code follows OCF's coding style guidelines
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have checked my code and corrected any misspellings

[peterdudfield]

Ill close this due to openclimatefix/quartz-frontend#712