Pin a nightly rust for our CI/CD

[ghzlatarev]

For reference - https://github.com/AcalaNetwork/Acala/blob/master/.github/workflows/test.yml#L39

[ghzlatarev]

Revert the CI workaround #571 which pins the tests and publish-draft-release workflows to:

rustup toolchain install nightly-2022-07-10-x86_64-unknown-linux-gnu
rustup target add wasm32-unknown-unknown --toolchain nightly-2022-07-10-x86_64-unknown-linux-gnu

[Dengjianping]

Cargo supports [toolchain] section.

[toolchain]
channel = "nightly-2022-07-10"
components = [ "rustfmt", "clippy" ]
targets = [ "wasm32-unknown-unknown" ]

[Garandor]

resolved by eb05731