fix: use string type for extraDependencies.dev in gen.yaml

Speakeasy v2 validates that extraDependencies.dev must be a string,
not an object. Changed from {} to empty string.

Co-Authored-By: AJ Steers <aj@airbyte.io>

Author: devin-ai-integration[bot]

gen.yaml

@@ -17,7 +17,7 @@ python:
   additionalDependencies:
     dependencies: {}
     extraDependencies:
-      dev: {}
+      dev: ""
   author: Airbyte
   clientServerStatusCodesAsErrors: true
   defaultErrorName: SDKError