switch to dtolnay toolchain

[salman01zp]

Summary of changes

• Use dtolnay/rust-toolchain instead of actions-rs/toolchain

Reference issue to close (if applicable)

Closes

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Code Checklist

• [ ] Tested
• [ ] Documented

[salman01zp]

Tarpaulin failing with Error: error while parsing. Reported Issue here

[drewstone]

What's the state of this?

[salman01zp]

Had some issues with building tarpaulin for code coverage, but this should fix it now