Tests

Adding SparseArrays and `return_sparse` option to inits #109

Job	Run time
Tests (1, macos-latest) / Tests	5m 16s
Tests (1, ubuntu-latest) / Tests	6m 29s
Tests (1, windows-latest) / Tests	23m 31s
Tests (lts, macos-latest) / Tests	7m 30s
Tests (lts, ubuntu-latest) / Tests	10m 15s
Tests (lts, windows-latest) / Tests	19m 4s
Tests (pre, macos-latest) / Tests	2m 56s
Tests (pre, ubuntu-latest) / Tests	4m 16s
Tests (pre, windows-latest) / Tests	21m 8s
	1h 40m 25s

Provide feedback