v2.0a8

• Adds support for StreamedContent with specific content length; fixing #374 both on the client and the server side.
• Fixes #373, about missing closing ASGI message when an async generator does not yield a closing empty bytes sequence (b"").
• Makes version dynamic in pyproject.toml, simplifying how the version can be queried at runtime (see #362).
• Fixes #372. Use the ASGI scope root_path when possible, as base_path.
• Fixes #371. Returns status 403 Forbidden when the user is authenticated but not authorized to perform an action.
• Fixes TypeError when writing a request without host header.
• Adds support for Pydantic v2: meaning feature parity with support for Pydantic v1 (generating OpenAPI Documentation).
• Adds support for Union types in sub-properties of request handlers input and output types, for generating OpenAPI Documentation, both using simple classes and Pydantic #389