Bump major version of mailbox update client to avoid startup failure
Test instructions:
- Check out commit 9f839d9d ("Merge branch '2309-troubleshooting-wizard' into 'master')
- Start Briar, create an account and sign out
- Check out commit b3dcde91 ("Merge branch '2301-update-contacts-about-change-in-mailbox-versions-that-client-supports' into 'master')
- Start Briar and sign in
- Expected: Signing in fails, startup failure screen is shown
- Check out this branch
- Start Briar and sign in
- Expected: Signing in succeeds, startup failure screen is not shown
Closes #2320 (closed)