For upgrade installations, it can be easily done via Universal Plugin Manager (Manage apps).
There are two ways to do this:
Automatic upgrade installation via the Git Integration app Upgrade button, or
Manual upgrade installation via the UPM ➜ Upload App:
Watch the video below on how to update your version of Git Integration for Jira app via UPM (Universal Plugin Manager).
The updating process is demonstrated in two chapters:
Automatic updating via UPM (0:05)
Manual updating via UPM (0:48)
More on Git Integration for Jira installation
Installation and updating (this page)