I’m currently running on firmware version 1.6.126. How do I update to the latest version?
Welcome to the Wyze User Community Forum @waterhouse! 
According to the Wyze Firmware Release & Updates Notes Webpage, It seems that there is no current updates available for your version.
Your version was not listed in the list. Is that a Beta Version? If so, the updates for those on Beta have not yet been released:
Note: This firmware will start as only available to a portion of people currently using firmware 1.6.113. The rest of eligible vacuums will be given access to the firmware update later. People using a different beta firmware version will be merged at a later time and will receive more information about the process then.
The next version released was 1.6.202 (March 22, 2022).
Note: This firmware will only be available for vacuums using the 1.6.199 firmware version. This will be a double update where the 1.6.199 version is installed before the vacuum updates to 1.6.202.
If you are in the Beta Program, Beta Updates will appear as a Firmware Available popup when you open the vacuum or it will be listed as available in the Firmware Update list in the Account menu.
If you are not in the Beta Program, you will be notified in the same two ways, but only for production releases.
People using a different beta firmware version will be merged at a later time and will receive more information about the process then.
This has been years though, how can we get an update?