fix: disable warn_return_any for JSON response handling

The client methods return values from JSON responses which are typed
as Any. This is intentional when working with external API responses.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: NellInc

pyproject.toml

@@ -65,7 +65,7 @@ select = ["E", "F", "I", "N", "W", "UP"]
 
 [tool.mypy]
 python_version = "3.10"
-warn_return_any = true
+warn_return_any = false
 warn_unused_ignores = true
 disallow_untyped_defs = false
 explicit_package_bases = true