refactor: clippy::must_use_candidate #982

Job	Run time
Clippy stable	39s
Test stable ubuntu-latest	58s
Release x86_64-unknown-linux-gnu	50s
Test stable macos-latest	53s
Release aarch64-unknown-linux-gnu	43s
Features stable ubuntu-latest	3m 54s
Clippy beta	49s
Test stable windows-latest	2m 35s
Release armv7-unknown-linux-gnueabihf	43s
Features stable macos-latest	3m 47s
Clippy nightly	44s
Test beta ubuntu-latest	1m 6s
Release arm-unknown-linux-gnueabihf	1m 19s
Features stable windows-latest	7m 5s
Test beta macos-latest	1m 3s
Release riscv64gc-unknown-linux-gnu	42s
Features beta ubuntu-latest	4m 6s
rustfmt	4s
Test beta windows-latest	2m 30s
Features beta macos-latest	3m 59s
Release x86_64-apple-darwin	29s
Test nightly ubuntu-latest	55s
Features beta windows-latest	6m 56s
Release aarch64-apple-darwin	27s
Test nightly macos-latest	52s
Release x86_64-pc-windows-msvc	2m 2s
Release aarch64-pc-windows-msvc	1m 6s
Test nightly windows-latest	2m 3s
	53m 19s

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