[CI] Pin specific rustfmt version

[CosminPerRam]

Pins a specific nightly version to fix errors in CI regarding version mismatch. Also reorders the check flow to move formatting to the 2nd last place.

[Douile]

You need to specify the specific version after cargo. So cargo +nightly-2023-03-01 fmt

[CosminPerRam]

Thanks, it works, I expected it to automatically pickup the version.