Caps mcp<2 so a fresh install resolves a working SDK.
The 2026-07-28 MCP spec makes the protocol stateless, and MCP Python SDK v2.0.0 removes the mcp.server.fastmcp import path outright (in-SDK FastMCP became MCPServer). ariadne.mcp_server imports it, so the previously uncapped mcp>=1.2 would break at import once mcp 2.x became the resolver default. No behaviour change.