CI: Ensure code coverage reporting will work in February 2022 and beyond

[fingolfin]

See https://github.com/gap-actions/process-coverage/issues/10

[codecov[bot]]

Codecov Report

Merging #11 (546c8c8) into master (84194f5) will decrease coverage by 77.78%. The diff coverage is n/a.

@@             Coverage Diff             @@
##           master      #11       +/-   ##
===========================================
- Coverage   92.01%   14.23%   -77.79%     
===========================================
  Files          16        8        -8     
  Lines      180360    16870   -163490     
===========================================
- Hits       165956     2401   -163555     
- Misses      14404    14469       +65     

Impacted Files	Coverage Δ
gap/realweyl.gi	0.00% <0.00%> (-11.87%)	:arrow_down:
gap/sqrt.gi	68.99% <0.00%> (-8.08%)	:arrow_down:
gap/nilpotentOrbits.gi	7.70% <0.00%> (-5.25%)	:arrow_down:
gap/realtheta.gi	0.00% <0.00%> (-3.81%)	:arrow_down:
gap/realforms.gi	31.59% <0.00%> (-2.94%)	:arrow_down:
gap/carrierrtsys.gi	21.01% <0.00%> (-2.50%)	:arrow_down:
gap/cartandecomp.gi	68.48% <0.00%> (-1.68%)	:arrow_down:
gap/forms.gi	6.47% <0.00%> (-0.02%)	:arrow_down:
gap/cartandecomp.gd
gap/realTriples.db
... and 6 more