Remove @schell from CODEOWNERS #1403

Job	Run time
Difftest (macOS-latest)	15m 0s
Test (windows-latest)	18m 10s
Compiletest (ubuntu-latest)	8m 3s
Android (ubuntu-latest, aarch64-linux-android)	8m 20s
Lint	5m 58s
Difftest (windows-latest)	26m 30s
Difftest (ubuntu-latest)	14m 30s
Test (ubuntu-latest)	11m 28s
cargo-deny	1m 29s
Test (macOS-latest)	15m 41s
Compiletest (windows-latest)	19m 32s
Compiletest (macOS-latest)	14m 42s
test_success	3s
	2h 39m 26s

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