docs: update Voyager dependency versions to 2.1.1

[ruturajjadhav07]

Description

The README previously listed version 2.1.0 for Maven and SBT dependencies. The latest release of Voyager is 2.1.1.

This PR updates the dependency versions in the installation instructions for Java (Maven) and Scala (SBT) to match the latest release, ensuring that users installing Voyager will get the most up-to-date version with all recent fixes and improvements.

No code changes were made—this update is purely for documentation accuracy.

Related Issues

None

Changes Made

• Updated Maven dependency version from 2.1.0 → 2.1.1
• Updated Scala SBT dependency version from 2.1.0 → 2.1.1

Testing

Not applicable

Checklist

• [ ] My code follows the code style of this project.
• [x] I have added and/or updated appropriate documentation (if applicable).
• [ ] All new and existing tests pass locally with these changes.
• [ ] I have run static code analysis (if available) and resolved any issues.
• [ ] I have considered backward compatibility (if applicable).
• [ ] I have confirmed that this PR does not introduce any security vulnerabilities.

Additional Comments

This PR is purely a documentation update to ensure the README matches the latest release.