'characteristic' endpoint now contains 31 in 'possible_values' when appropriate

[fissionprime]

The while loop which generates the 'possible_values' field for the 'characteristic' endpoint does not allow for a value of 31 (the maximum IV value) to be added to 'possible_values'. Adjusting the value this loop compares against rectifies the issue. This specifically affects the second row in the table on https://bulbapedia.bulbagarden.net/wiki/Characteristic , which corresponds to the characteristics with IDs 7-12. Previously their 'possible_values' fields returned [1,6,11,16,21,26]. After changes, they return [1,6,11,16,21,26,31].

Also included is a new test, which tests that 'possible_values' contains the correct values for each of the 5 possible values of 'gene_modulo'.

All tests pass after changes, and when running the API locally, produces the expected results.

[fissionprime]

Note: this fix should close #628

[Naramsim]

Thanks!

[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 you will be able to review the entire API.

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.

You can see the Pull Request deployed at our staging environment when CircleCI deploy will be finished (check the started time of the last build).