If you have an external Z-Wave stick and a Windows PC, you could use the Z-Wave PC Controller software to perform the update. (You'd have to remove the dimmer from Hubitat, pair it to that, then remove it and pair it back; or you could try adding the stick as a secondary controller to Hubitat.) Here's how to do that:
Alternatively, you can use Hubitat's unofficial "Z-Wave Firmware Updater" tool from this thread:
For the LZW31-SN, I'd actually use the "advanced"/binary updater instead since there are two "targets" you need for the Inovelli dimmers, and only that version will let you do both. That version is in this post: [RELEASE] Z-Wave Firmware Updater - #860 by bcopeland
You can use Inovelli's instructions and the URLs they provide for both the target 0 and target 1 updates. Unfortunately, they didn't include the target 1 update in the 1.48 doc, so you'll have to find it in 1.47 (it didn't change): Knowledge Base Redirect – Inovelli.
Inovelli's general Hubitat instructions are here, except they don't seem to have written them with both targets in mind (and are using the original version of the updater--I'd use the newer one I linked to above), so you'll have to remember that the .OTZ file goes to target 0 and the .BIN file to target 1:
Sorry if this is confusing...looks like there isn't one spot that has everything. 
