HouseKeeping add crvOBTC updated strategy

[saltyfacu]

HouseKeeping add crvOBTC strategy latest update from this address: 0x7F83935EcFe4729c4Ea592Ab2bC1A32588409797

Should follow similar housekeeping PRs including:

• Refactoring interfaces
• Update calls in code to use interfaces
• CI should be green before merging

Example PRs to follow https://github.com/iearn-finance/yearn-protocol/pull/89/files

[saltyfacu]

Closing in favor of #105