as f-strings are heavily used now, compatibility to py35 can be removed Change-Id: I1ae4912ad4cbde8419b74845217943bd061053f3 Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/32754 Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de> Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de> Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>