Remove duckduckgo search tools and agents (#6783)

Author: ekzhu

python/packages/autogen-ext/pyproject.toml

@@ -155,13 +155,6 @@ canvas = [
     "unidiff>=0.7.5",
 ]
 
-duckduckgo-search = [
-    "httpx>=0.27.0",        
-    "beautifulsoup4>=4.12.0", 
-    "html2text>=2024.2.26",  
-    "autogen-agentchat==0.6.3",
-]
-
 [tool.hatch.build.targets.wheel]
 packages = ["src/autogen_ext"]