fix(openapi): Mark Region.main_generation as nullable

[santichausis]

The Hisui region (and potentially others) have no main_generation, causing the API to return null for this field. The OpenAPI spec was incorrectly marking it as required and non-nullable.

Changes:

• Add nullable: true to Region.main_generation
• Remove main_generation from the required array

Fixes#1397

[Naramsim]

Hi, did you manually change the spec or did you run the generator?

[santichausis]

Hi, did you manually change the spec or did you run the generator?

I manually edited the spec this time, but I've updated the PR to make the change in the serializer instead (allow_null=True on main_generation), so the spec can be regenerated from the source.

[Naramsim]

Hi can you run the linter and commit the changed openapi.yml?

[santichausis]

Done! Ran black on the serializer and regenerated the openapi.yml.

[pokeapi-machine-user]

A PokeAPI/api-data refresh has started. In ~45 minutes the staging branch of PokeAPI/api-data will be pushed with the new generated data.

The staging branch will be deployed in our staging environment and the entire API will be ready to review.

A Pull Request (master<-staging) will be also created at PokeAPI/api-data and assigned to the PokeAPI Core team to be reviewed. If approved and merged new data will soon be available worldwide at pokeapi.co.

[pokeapi-machine-user]

The updater script has finished its job and has now opened a Pull Request towards PokeAPI/api-data with the updated data.

The Pull Request can be seen deployed in our staging environment when CircleCI deploy will be finished (check the start time of the last build).