Add bots claim-draw, bots claim-victory and board claim-draw endpoints

[jquiaios]

This PR is a small part of #6 and implements

• bots.claim-draw
• bots.claim-victory
• client.board.claim_draw

Some notes about those three endpoints:

• They all return None
• They all require an authenticated user + in-progress game, so no tests added

Checklist when adding a new endpoint

• Added new endpoint to the README.md
• Ensured that my endpoint name does not repeat the name of the client. Wrong: client.users.get_user(), Correct: client.users.get()
• Typed the returned JSON using TypedDicts in berserk/types/, example
• Written tests for GET endpoints not requiring authentification. Documentation, example
• Added the endpoint and your name to CHANGELOG.md in the To be released section (to be created if necessary)