There is no way to get the iOS version legitimately.
First, you need to check if your iPhone can be jailbroken. There is a comprehensive list of jailbreaks with their corresponding jailbreaks here. If your iOS version is not jailbreakable, you need to stop updating and wait for a jailbreak to become available (if it ever does.)
If you cannot jailbreak, you can still sideload MCSM Seasons One and Two, but they will only stay for 1 week, and you'll need to sideload them again. As for sideloading, you need to download iTunes on your PC and install a sideloading application. I'd recommend Sideloadly.
You can download the .ipa files from the Telltale iOS Archive
Season One
Want v1.4.0 instead -> Here.
Season Two
Want v1.6.0 instead -> Here.
You can find the episodes here.
Or alternatively, in one of those mirrors: Season 1 #1, Season 2 #1, Mirror #2
Important: When sideloading the games: Click "Advanced Options" under the Apple ID option and make sure file sharing is turned on.