fix: cap mcp dependency to <2 to prevent breaking API changes

[PiedPiper911]

Problem

Fixes #8014

The mcp Python SDK released version 2.0.0 with breaking API changes:

• streamablehttp_client renamed to streamable_http_client
• Return tuple changed from 3-tuple to 2-tuple
• read_timeout_seconds changed from timedelta to float
• camelCase attributes renamed to snake_case (inputSchema -> input_schema, isError -> is_error)

Since autogen-ext declares mcp>=1.11.0 with no upper bound, fresh installs resolve to mcp==2.0.0 and immediately break.

Solution

Cap the dependency at mcp>=1.11.0,<2 in pyproject.toml to prevent automatic upgrade to the incompatible 2.x line.

This is the minimal short-term fix. A full MCP 2.0 migration can be done as a follow-up.

Changes

• python/packages/autogen-ext/pyproject.toml: Changed mcp>=1.11.0 to mcp>=1.11.0,<2