GHSA-q382-vc8q-7jhj: Improper handling of null Unicode character when parsing JSON in github.com/modelcontextprotocol/go-sdk

The Go SDK recently transitioned to the segmentio/encoding library for JSON parsing in version 1.3.1. While this change addressed both case-insensitivity and ASCII folding issues, the new parser implemented aggressive key matching that treated keys with null Unicode characters appended at the end as equivalent to their base strings.