chore: update codecov gha to v2

[tim-mwangi]

Description

Codecov bash uploader is being deprecated and is currently in the brownout phase. We need to upgrade to the v2 gh action in all repos.

More info: https://about.codecov.io/blog/codecov-uploader-deprecation-plan/

[codecov]

Codecov Report

Merging #39 (865cbb3) into main (05eeef7) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main      #39   +/-   ##
=========================================
  Coverage     69.57%   69.57%           
  Complexity      106      106           
=========================================
  Files            15       15           
  Lines           562      562           
  Branches         33       33           
=========================================
  Hits            391      391           
  Misses          151      151           
  Partials         20       20           

Flag	Coverage Δ
unit	69.57% <ø> (ø)

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[github-actions]

Unit Test Results

  9 files  ±0    9 suites  ±0   8s ⏱️ -2s
31 tests ±0  31 ✔️ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit dc08ffe. ± Comparison against base commit 05eeef7.