test: add tests based on mincer2 and minceex

[jodavies]

No description provided.

[coveralls]

coverage: 55.77% (+0.5%) from 55.224%
when pulling 1b5988c on jodavies:test-extra-mincer
into 4e3567c on form-dev:master.

[jodavies]

@tueda are you happy with the changes in actions.yml? It means we wget https://github.com/form-dev/form-packages/archive/refs/tags/v1.0.0.tar.gz twice, but allows one to enable color and mincer independently in principle (not that we currently need to do this).

[tueda]

I think this is a reasonable choice for now. In principle, they could be combined, but doing so requires some changes and a decision on whether to use a single package or write more complex code that enables a single download to be reused for the two packages.