readme: drop 2.4, 2.5 support
readme: drop 2.4, 2.5 support

tonycpsu/urwid,ivanov/urwid,inducer/urwid,douglas-larocca/urwid,ivanov/urwid,inducer/urwid,rndusr/urwid,harlowja/urwid,douglas-larocca/urwid,urwid/urwid,hkoof/urwid,rndusr/urwid,harlowja/urwid,wardi/urwid,wardi/urwid,foreni-packages/urwid,drestebon/urwid,harlowja/urwid,drestebon/urwid,hkoof/urwid,ivanov/urwid,tonycpsu/urwid,hkoof/urwid,drestebon/urwid,tonycpsu/urwid,inducer/urwid,rndusr/urwid,foreni-packages/urwid,urwid/urwid,douglas-larocca/urwid,foreni-packages/urwid,urwid/urwid,wardi/urwid