Revert "ci(travis): Bump Luarocks install to 3.3.1"
Revert "ci(travis): Bump Luarocks install to 3.3.1"

This reverts commit cd7a92c03f0553a7deb1e453afe4e4e393cdacf4.

Can be re-introduced when this upstream bug is fixed:

https://github.com/luarocks/luarocks/issues/1204

alerque/sile,alerque/sile,alerque/sile,alerque/sile