Relicense the library to MIT/Apache 2.0 #193

Job	Run time
Check spelling	1m 31s
Check formatting (ubuntu-latest)	1m 6s
Integration tests (ubuntu-latest)	46s
Check formatting (macos-latest)	3m 30s
Check dependencies (ubuntu-latest)	4m 8s
Integration tests (macos-latest)	1m 13s
Clippy lints (ubuntu-latest)	1m 22s
Check formatting (windows-latest)	3m 14s
Check dependencies (macos-latest)	6m 24s
Integration tests (windows-latest, true)	2m 27s
Clippy lints (macos-latest)	1m 41s
Check dependencies (windows-latest)	8m 2s
Clippy lints (windows-latest)	3m 4s
Unit tests (ubuntu-latest)	1m 19s
Unit tests (macos-latest)	1m 58s
Unit tests (windows-latest)	3m 58s
	45m 43s

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