Remove dependency on nose, which is unmtainained and soon to be broken.

[mcepl]

Fixes #294

Further integration into CI, etc. are left as an exercise for the reader.

[codecov-commenter]

Codecov Report

Merging #295 into master will decrease coverage by 0.77%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #295      +/-   ##
==========================================
- Coverage   90.52%   89.75%   -0.78%     
==========================================
  Files          60       44      -16     
  Lines        4286     3817     -469     
==========================================
- Hits         3880     3426     -454     
+ Misses        406      391      -15     

Impacted Files	Coverage Δ
tests/test_pictures.py
tests/test_utils_dumps_list.py
tests/test_no_fontenc.py
tests/test_no_list_as_data.py
tests/test_quantities.py
tests/test_utils_fix_filename.py
tests/test_no_inputenc.py
tests/test_inheritance.py
tests/test_no_lmodern.py
tests/test_jobname.py
... and 5 more