AST-1602 Bump version to 1.6.1, Use EveryBeam 0.6.1; Simplify CI
- Using EveryBeam 0.6.1 avoids conflicts with python-casacore, since both python modules contain Casacore libraries.
- Remove 'build' CI jobs since the 'test' jobs already build LSMTool, too.
- Fix 'test' CI jobs: They previously overwrote 'before_script', which caused failures.
Edited by Maik Nijhuis