Update edition to 2021 & specify optional dependency pathway unambiguously #35
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Couple of small "maintenance" things:
dep:cratesyntax to specify the dependency onserdeby theserde_implfeaturepubvisibilities#[inline]attributes onserializeandvisit_seqin the ser/de implementations. These can already be inlined even without LTO cross-crate because they are generic. There is also little reason to explicitly hint these to encourage additional inlining without a reason grounded in data due to their nature.