fix: export HttpError from mcp package

Author: MaxwellCalkin

src/mcp/__init__.py

@@ -4,7 +4,7 @@
 from .client.stdio import StdioServerParameters, stdio_client
 from .server.session import ServerSession
 from .server.stdio import stdio_server
-from .shared.exceptions import MCPError, UrlElicitationRequiredError
+from .shared.exceptions import HttpError, MCPError, UrlElicitationRequiredError
 from .types import (
     CallToolRequest,
     ClientCapabilities,
@@ -81,6 +81,7 @@
     "ErrorData",
     "GetPromptRequest",
     "GetPromptResult",
+    "HttpError",
     "Implementation",
     "IncludeContext",
     "InitializeRequest",