Bump rmp-serde from 1.1.2 to 1.2.0 #2000

Job	Run time
Rustfmt (stable)	10s
clippy_check (ubuntu-latest, stable)	25s
Build and Test (ubuntu-latest, 1.65)	2m 7s
clippy_check (ubuntu-latest, nightly)	58s
Build and Test (ubuntu-latest, 1.70)	2m 23s
clippy_check (windows-latest, stable)	1m 43s
Build and Test (ubuntu-latest, 1.75)	2m 9s
Build and Test (ubuntu-latest, stable)	2m 24s
Build and Test (ubuntu-latest, beta)	1m 44s
Build and Test (ubuntu-latest, nightly)	2m 7s
Build and Test (windows-latest, 1.65)	2m 11s
Build and Test (windows-latest, 1.70)	2m 9s
Build and Test (windows-latest, 1.75)	2m 11s
Build and Test (windows-latest, stable)	2m 11s
clippy_check (windows-latest, nightly)	1m 34s
Build and Test (windows-latest, beta)	2m 9s
Build and Test (windows-latest, nightly)	2m 10s
Tests result	1s
	30m 46s

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