Upgrade supported version of anthropic SDK

 - supports newer series of Anthropic SDKs which use overriden Promise classes and Stream classes
 - enables the mostly-finished streaming chat completion support in the implementation and tests

Author: airhorns

package-lock.json

@@ -45,7 +45,7 @@
     "tslib": "^2.8.1"
   },
   "devDependencies": {
-    "@anthropic-ai/sdk": "^0.32.1",
+    "@anthropic-ai/sdk": "^0.50.4",
     "@pollyjs/adapter-node-http": "^6.0.6",
     "@pollyjs/core": "^6.0.6",
     "@pollyjs/persister-fs": "^6.0.6",