feat(jsonrpc): switch to spec 0.6.0 #1040

Job	Run time
no-std build	1m 33s
no-std build	1m 33s
no-std build	1m 33s
Unix tests (ubuntu-latest, stable)	12m 43s
Unix tests (ubuntu-latest, stable)	12m 47s
Unix tests (ubuntu-latest, stable)	2m 1s
WASM tests	4m 22s
WASM tests	4m 22s
WASM tests	4m 22s
Unix tests (ubuntu-latest, nightly)	12m 42s
Unix tests (ubuntu-latest, nightly)	2m 5s
Unix tests (ubuntu-latest, nightly)	2m 5s
Windows tests (stable, x86_64-pc-windows-gnu)	7m 22s
Windows tests (stable, x86_64-pc-windows-gnu)	7m 22s
Windows tests (stable, x86_64-pc-windows-gnu)	7m 22s
Unix tests (macos-11, stable)	12m 43s
Unix tests (macos-11, stable)	12m 50s
Unix tests (macos-11, stable)	3m 49s
Windows tests (stable, x86_64-pc-windows-msvc)	14m 47s
Windows tests (stable, x86_64-pc-windows-msvc)	14m 39s
Windows tests (stable, x86_64-pc-windows-msvc)	8m 51s
Unix tests (macos-11, nightly)	12m 42s
Unix tests (macos-11, nightly)	9m 8s
Unix tests (macos-11, nightly)	9m 8s
Windows tests (nightly, x86_64-pc-windows-gnu)	14m 41s
Windows tests (nightly, x86_64-pc-windows-gnu)	14m 36s
Windows tests (nightly, x86_64-pc-windows-gnu)	11m 41s
Windows tests (nightly, x86_64-pc-windows-msvc)	14m 39s
Windows tests (nightly, x86_64-pc-windows-msvc)	5m 18s
Windows tests (nightly, x86_64-pc-windows-msvc)	5m 18s
	4h 9m 4s

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