Add update_tag_name method

[n7studios]

Summary

Adds a method for updating a tag name.

Testing

• testUpdateTagName: Test that update_tag_name() returns the expected data.
• testUpdateTagNameWithInvalidTagID: Test that update_tag_name() throws a ClientException when an invalid tag ID is specified.
• testUpdateTagNameWithBlankName: Test that update_tag_name() throws a ClientException when a blank tag name is specified.

Checklist

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• The code passes when running PHPStan
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)