You don't necessarily need to connect your air-gapped device to the internet (because it voids the actual purpose) to upgrade your electrum because it can be done completely offline.

Download the latest version of Electrum from https://electrum.org/#download and then verify the signatures before installing it.

Then copy the downloaded file to your air-gapped device and install it, then restore your wallet with your seeds "Standard Wallet -> I already have a seed".

Then go to  "Wallet -> Info" and get your "Master Public Key"

After this go to your device which is connected to the internet create the "watch-only" wallet (Standard Wallet -> "Use a Master Key)

By this method device will be never connected to the internet so you no need to worry about your seeds being exposed to malware or anything.