updated Ubuntu runner label in push.yml

[nlrcomcast]

1. Ubuntu 22.04 not compatible for parodus, so Runner label we changed from ubuntu-latest to ubuntu-20.04.
2. 'codecov' python package is deprecated, so we changed to 'coverage'.

[codecov]

Codecov Report

Merging #438 (22bca0d) into master (0fd3b76) will decrease coverage by 0.79%.
Report is 187 commits behind head on master.
The diff coverage is 56.68%.

@@            Coverage Diff             @@
##           master     #438      +/-   ##
==========================================
- Coverage   93.17%   92.39%   -0.79%     
==========================================
  Files          52       52              
  Lines        9514     9734     +220     
==========================================
+ Hits         8865     8994     +129     
- Misses        649      740      +91     

Files	Coverage Δ
src/ParodusInternal.c	74.69% <100.00%> (ø)
src/auth_token.c	99.23% <100.00%> (+0.01%)	⬆️
src/conn_interface.c	90.29% <100.00%> (+0.19%)	⬆️
src/crud_internal.c	93.22% <100.00%> (ø)
src/downstream.c	76.57% <100.00%> (+0.27%)	⬆️
src/nopoll_handlers.c	96.77% <100.00%> (+0.05%)	⬆️
src/nopoll_helpers.c	97.36% <100.00%> (+0.14%)	⬆️
tests/test_config.c	94.46% <100.00%> (+0.06%)	⬆️
tests/test_crud_internal.c	99.81% <100.00%> (ø)
tests/test_heartBeatTimer.c	100.00% <ø> (ø)
... and 15 more