Bump serde from 1.0.199 to 1.0.200 #883

Job	Run time
check	7m 12s
matrix	45s
test-client-check	3m 54s
test-client-matrix	53s
test-client-clippy	1m 21s
Build test client (x86_64-unknown-linux-musl)	1m 58s
Build test client (i686-unknown-linux-musl)	2m 9s
Build test client (armv7-unknown-linux-musleabihf)	2m 8s
Build test client (aarch64-unknown-linux-musl)	1m 57s
Build test client (x86_64-unknown-freebsd)	2m 0s
Build test client (.exe, x86_64-pc-windows-gnu)	2m 2s
Check MSRV	2m 43s
tests	14m 13s
clippy	2m 43s
build (x86_64-unknown-linux-musl)	12m 4s
build (i686-unknown-linux-musl)	5m 12s
build (armv7-unknown-linux-musleabihf)	11m 34s
build (aarch64-unknown-linux-musl)	11m 45s
build (x86_64-unknown-freebsd)	12m 13s
Package nightly release	26m 13s
	2h 4m 59s

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