Update CI/CD workflows

[Atmelfan]

The workflow uses actions/checkout@v2 and action-rs/toolchain@v1, both throws warnings and uses deprecated commands.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 76.00%. Comparing base (718dfa8) to head (eea395a).

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #24      +/-   ##
==========================================
+ Coverage   67.13%   76.00%   +8.86%     
==========================================
  Files          33       27       -6     
  Lines        1771     2592     +821     
==========================================
+ Hits         1189     1970     +781     
- Misses        582      622      +40     

Flag	Coverage Δ
unittests	76.00% <ø> (?)

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