Add GitKraken to third-party mcp server list

[cmgriffing-at-gitkraken]

Description

This change adds GitKraken to the third-party servers list in its appropriate position alphabetically.

Motivation and Context

Motivation is to increase completeness of third-party listings.

How Has This Been Tested?

The third-party MCP server has been tested in Claude Desktop, Cursor, Windsurf, Warp, and VS Code Copilot.

Breaking Changes

None.

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 Protocol Documentation
• My changes follows MCP security best practices
• I have updated the server's README accordingly
• I have tested this with an LLM client
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have documented all environment variables and configuration options

[cmgriffing-at-gitkraken]

Apologies for the "Unverified" tag on my commit. I had git configured to use my gitkraken email, but the signing was using the users.noreply.github.com address. I have since fixed it locally, but the old commit persists. I could try again with a fresh pr and commit if it's an issue.