Allow specifying the server version

[kfischer-okarin]

I added a constructor parameter to the Server class to specify a server version.

Motivation and Context

Currently the server uses the gem version as version returned to the client. But the gem is just the framework used to built the actual server.

How Has This Been Tested?

I tried it out a dummy server out with the official mcp inspector.

Breaking Changes

It's an additional optional argument so it should not break anything.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[topherbullock]

Thanks @kfischer-okarin !