The `options()`, `head()`, `post()`, `put()`, `patch()`, and
`delete()` methods on both `Client` and `AsyncClient` were missing
`| None` in their `auth` parameter type annotation. This makes them
inconsistent with `get()`, `request()`, `send()`, and `stream()`
which all accept `auth: AuthTypes | UseClientDefault | None`.

Passing `auth=None` to explicitly opt out of authentication is a
valid use case that was already supported at runtime (via `request()`)
but the type annotations on these methods would incorrectly flag it.