fix(ci) only test LuaJIT 2.0.5 as a released version
fix(ci) only test LuaJIT 2.0.5 as a released version

This disables the master branch, the released version is already
tested. So the impact should me minimal to non-existent since
probably nobody uses the master branch. As apposed to the
2.1.x master branch for which there is no release yet.

Olivine-Labs/busted