refactor: s/Expected<Out>/Self #248

Job	Run time
cargo-deny	19s
Rustfmt (stable)	3s
Clippy (stable)	28s
Check (ubuntu-latest, stable)	30s
Clippy (beta)	34s
Test Suite (ubuntu-latest, stable)	50s
Check (ubuntu-latest, beta)	36s
Test Suite (ubuntu-latest, beta)	55s
Check (windows-latest, stable)	1m 19s
Test Suite (windows-latest, stable)	1m 52s
Check (windows-latest, beta)	1m 10s
Test Suite (windows-latest, beta)	1m 37s
Check (macOS-latest, stable)	42s
Test Suite (macOS-latest, stable)	1m 9s
Check (macOS-latest, beta)	52s
Test Suite (macOS-latest, beta)	1m 32s
	14m 28s

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