#6 Add Tournaments.get_played

[nstillman-te]

Part of #6.

Adds GET /api/user/{username}/tournament/played: client.tournaments.get_played(username, nb=..., performance=...) returning a list of tournaments played by the user with player stats. Typed with ArenaTournamentPlayed / ArenaTournamentPlayer; VCR test plus requests-mock test for query params.

Checklist when adding a new endpoint

• Added new endpoint to the README.rst
• 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.rst in the To be released section (to be created if necessary)