Add missing Coinbase RATEs

[nicjansma]

Proposed change

Coinbase exposes the exchange rates they support querying at https://api.coinbase.com/v2/exchange-rates

I've compared this list to const.py and have added all missing RATEs.

I was unable to verify if all of these rates imply wallet support, so I did not make any changes to WALLETS.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: n/a
• This PR is related to issue: n/a
• Link to documentation pull request: n/a

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[probot-home-assistant]

Hey there @TomBrien, mind taking a look at this pull request as it has been labeled with an integration (coinbase) you are listed as a code owner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[TomBrien]

Looks good to me. Thanks for contributing to the project :)

[homeassistant]

Hi @nicjansma,

It seems you haven't yet signed a CLA. Please do so here.

Once you do that we will be able to review and accept this pull request.

Thanks!

[github-actions]

There hasn't been any activity on this pull request recently. This pull request has been automatically marked as stale because of that and will be closed if no further activity occurs within 7 days.
Thank you for your contributions.

[TomBrien]

This should be good to merge now the the CLA has been signed

[MartinHjelmare]

Thanks!