Added workflows to test Linux, Windows, and Mac builds. #35

All 14 440 tests pass in 4m 52s

14 440 tests ±0 14 440 ✔️ ±0 4m 52s ⏱️ -47s
        1 suites ±0         0 💤 ±0
        1 files ±0         0 ❌ ±0

Results for commit 7df94a7. ± Comparison against earlier commit 6feefa9.