Update gitpython library for git mcp server

[cblecker]

Description

Updates the gitpython library to pull in a number of bug fixes, as well as fixes a test that used the hardcoded "master" default branch.

Server Details

• Server: git
• Changes to: resources

Motivation and Context

Pulls in bug fixes for the gitpython library, and ensures that tests pass regardless of the git version used (the default branch name was changed from "master" to "main" in git).

How Has This Been Tested?

Local tests pass

Breaking Changes

No, there are no breaking changes

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

Additional context

• Moved tool.uv.dev-dependencies field (used in pyproject.toml) to dependency-groups.dev as the former is deprecated and uv was throwing a warning
• Bumped pyright to v1.1.407, per warning when running it
• Fix decode error as d.diff should be a string in gitpython 3.1.45+