Bump `base16ct` to v1 #38

Job	Run time
minimal-versions / minimal-versions	39s
set-msrv / set-msrv	4s
test (stable)	23s
build (1.85.0, thumbv7em-none-eabi)	24s
build (1.85.0, wasm32-unknown-unknown)	26s
test (1.85.0)	33s
build (stable, thumbv7em-none-eabi)	19s
build (stable, wasm32-unknown-unknown)	17s
	3m 5s

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