feat: Python SDK update for version 21.0.0

[ChiragAgg5k]

This PR contains updates to the Python SDK for version 21.0.0.

What's Changed

• Added: apps service for managing apps and app secrets
• Added: oauth2 service for the OAuth2 authorization, device, and token flows
• Added: device authorization grant parameters (verificationUrl, userCodeLength, userCodeFormat, deviceCodeDuration) to updateOAuth2Server
• Added: emailCanonical, emailIsFree, emailIsDisposable, emailIsCorporate, and emailIsCanonical to the User model
• Added: userAccessedAt to the Membership model
• Added: PolicyDenyCorporateEmail and deny-corporate-email to ProjectPolicyId
• Added: dedicatedDatabases.execute to ProjectKeyScopes
• Breaking: usage.listEvents now takes a required metrics array with resource, interval, and dimensions instead of queries and total
• Breaking: Replaced UsageEvent and UsageGauge models with UsageDataPoint and UsageMetric
• Updated: Send an Accept: application/json header on all requests

[greptile-apps]

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