check compatibility before update

[openforfuture]

In relation to what happen here:
element-hq/element-desktop#1505

I suggest to:

• check if the new update is compatible with the OS before downloading and updating (which means trashing the old version)
• if it's not, turn off auto-updates and advise the user about EOL or other reasons why cannot update anymore

basically, take care about the UX during breaking updates and avoid leaving the user with a broken app that instantly crashes, without explaining why and how can fix the situation (ex. use the previous version).