ci: add test for multiple os

[0xethsign]

Test project on multiple operating systems via matrix.
ref - casbin/casbin-rs#234

Signed-off-by: smrpn [email protected]

[0xethsign]

@hackerchai can you please approve a workflow run

[codecov-commenter]

Codecov Report

Merging #19 (3047c56) into master (6a5fd6b) will decrease coverage by 2.42%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #19      +/-   ##
==========================================
- Coverage   71.78%   69.35%   -2.43%     
==========================================
  Files           3        3              
  Lines         241      248       +7     
==========================================
- Hits          173      172       -1     
- Misses         68       76       +8     

Impacted Files	Coverage Δ
src/casbin_actor.rs	40.67% <0.00%> (-6.78%)	⬇️
tests/test_set_enforcer.rs	100.00% <0.00%> (ø)
tests/test_casbin.rs	94.95% <0.00%> (+0.26%)	⬆️

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[hackerchai]

lgtm

[hackerchai]

lgtm