fix: remove unnecessary Sized boundaries #935

Job	Run time
Rustfmt	17s
Clippy	1m 19s
Test Suite	2m 8s
Check	1m 39s
Cross compile (armv7-unknown-linux-gnueabihf)	15s
Cross compile (wasm32-unknown-unknown)	15s
Cross compile (powerpc64-unknown-linux-gnu)	11s
Cross compile (powerpc-unknown-linux-gnu)	17s
Check rustdoc intra-doc links	36s
	6m 57s

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