Prepare release version 0.8.0 (#424)

bump mcp kotlin-sdk to 0.8.0

## Checklist
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed

Author: devcrocod

gradle.properties

@@ -14,4 +14,4 @@ kotlin.mpp.enableCInteropCommonization=true
 kotlin.native.ignoreDisabledTargets=true
 
 group=io.modelcontextprotocol
-version=0.8.0-SNAPSHOT
+version=0.8.0