Since Conda now comes with the libmamba solver enabled by default it'll be less confusing for students if we just stick with Conda, which is what this PR does. The C++ implementation of Mamba can still contribute some small speed increase, but not enough that it's worth the possible confusion - I still mention it (plus the fact that Mamba colours its output) in the extra material, though, so interested students can use Mamba if they prefer.
Since Conda now comes with the libmamba solver enabled by default it'll be less confusing for students if we just stick with Conda, which is what this PR does. The C++ implementation of Mamba can still contribute some small speed increase, but not enough that it's worth the possible confusion - I still mention it (plus the fact that Mamba colours its output) in the extra material, though, so interested students can use Mamba if they prefer.