ci: move `nightly job` to the CI. (#770) #333

Job	Run time
set-image	1s
Build polkadot-staking-miner binary	5m 13s
Check documentation	1m 43s
Clippy	3m 29s
Check code using cargo-hack	2m 22s
Check formatting	1m 2s
Check staking-miner-playground	14m 23s
Run tests	6m 6s
Build and publish Docker image	33s
Test Docker image build	0s
	34m 52s

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