ci: move `nightly job` to the CI. #332

Job	Run time
set-image	1s
Build polkadot-staking-miner binary	4m 49s
Clippy	3m 12s
Check documentation	1m 31s
Check code using cargo-hack	2m 9s
Check formatting	1m 6s
Check staking-miner-playground	14m 30s
Run tests	5m 58s
Test Docker image build	24s
Build and publish Docker image	0s
	33m 40s

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