chore(ci/build): use matrix for builds

[wass3rw3rk]

should add a little speed boost for running the build workflow. it will parallelize building for each platform when possible - could even add arch into the mix.

ref: https://docs.github.com/en/actions/using-jobs/using-a-matrix-for-your-jobs

opportunity to do the same for release builds (on release/tag events). make build is baked into the release.sh script, so might need a bit of rework.

UPDATE:
comparing the build in this PR with the matrix addition versus another, it looks like we're shaving off almost 10 minutes of build time.

before

after

[codecov]

Codecov Report

Merging #452 (74cefb6) into main (e9c1fdf) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #452   +/-   ##
=======================================
  Coverage   86.00%   86.00%           
=======================================
  Files         133      133           
  Lines        5815     5815           
=======================================
  Hits         5001     5001           
  Misses        666      666           
  Partials      148      148           

[plyr4]

nice