ref(scope): Fix get_client typing (#3063)

The `Scope.get_client` method is typed as returning `sentry_sdk.client.BaseClient`, but because `sentry_sdk.client` was not imported, the type was resolved as `Any`. This change imports `sentry_sdk.client` to fix the type hints.

Author: szokeasaurusrex

Diff for: sentry_sdk/scope.py

@@ -1640,3 +1640,6 @@ def should_send_default_pii():
 
 # Circular imports
 from sentry_sdk.client import NonRecordingClient
+
+if TYPE_CHECKING:
+    import sentry_sdk.client