Ensure 11/25/25 MCP protocol is advertised in 2.14

[jlowin]

Enhancement

When 2.14 is released, we need to ensure that servers properly advertise the right protocol version; 2.14 will require mcp>=1.23 and FastMCP will implicitly target the 11/25/25 protocol spec.

[jlowin]

Confirmed this already works:

import asyncio
from fastmcp import Client, FastMCP

mcp = FastMCP("Test")

async def main():
    async with Client(mcp) as client:
        print(client.initialize_result.protocolVersion)

asyncio.run(main())
# 2025-11-25