update travis clang to 11#274

Merged

evaleev merged 3 commits into

evaleev/fix/travis-clang-versions

May 15, 2021

Commits on May 6, 2021

[travis] retiring clang-8, replacing with clang-9, updated repo package pack names
evaleev
committed

Commits on May 7, 2021

[travis] trying clang-11 now
evaleev
committed

Commits on May 15, 2021

[ci] disable clang builds due to broken travis ubuntu image
evaleev
committed