Ponder using TLS v1.3

[ahupowerdns]

Hi - I note that Intra (as downloaded from google play store yesterday) on Android 8.1 does not use TLSv1.3 - is this by design? It seems v1.3 would have advantages. On the PowerDNS DoH server I see Firefox use 1.3 successfully - although I of course do not see requests that fail to reach me.

[bemasc]

Intra currently uses OkHttp for all networking, and I believe that OkHttp uses the system's default TLS stack, so Intra can't use TLS 1.3 until the OS libraries gets TLS 1.3 support.

[mrsylerpowers]

Should be fixed with #174