add --channel flag and remove AWS Amplify legacy #14

Job	Run time
Test (ubuntu-latest)	59s
Build Check (x86_64-pc-windows-msvc)	3m 11s
Build Check (x86_64-unknown-linux-gnu)	1m 31s
Test (windows-latest)	2m 12s
Test (macos-latest)	49s
Build Check (aarch64-apple-darwin)	2m 15s
Format	6s
Build Check (x86_64-apple-darwin)	2m 47s
Clippy	37s
Check	40s
	15m 7s

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