Bump okhttp to the latest version.

[fesave]

To perform this issue is necessary to upgrade dav4Android.

[jesmrec]

Way to do this:

https://github.com/owncloud/android-library/blob/5607f76a1dd4ce9a02255db128c946ba37b466d3/owncloudComLibrary/build.gradle#L9

Library pointed there need to be upgraded first against the upstream one

CC @JuancaG05 @manuelplazaspalacio