docs: add Gem to readme

Author: idosal

README.md

@@ -7,7 +7,7 @@
 <p align="center">
   <a href="https://www.npmjs.com/package/@mcp-ui/server"><img src="https://img.shields.io/npm/v/@mcp-ui/server?label=server&color=green" alt="Server Version"></a>
   <a href="https://www.npmjs.com/package/@mcp-ui/client"><img src="https://img.shields.io/npm/v/@mcp-ui/client?label=client&color=blue" alt="Client Version"></a>
-  <a href="https://rubygems.org/gems/mcp_ui_server"><img src="https://img.shields.io/gem/v/mcp_ui_server?label=ruby-server&color=red" alt="Ruby Server SDK Version"></a>
+  <a href="https://rubygems.org/gems/mcp_ui_server"><img src="https://img.shields.io/gem/v/mcp_ui_server" alt="Ruby Server SDK Version"></a>
   <a href="https://gitmcp.io/idosal/mcp-ui"><img src="https://img.shields.io/endpoint?url=https://gitmcp.io/badge/idosal/mcp-ui" alt="MCP Documentation"></a>
 </p>