Update rusti-ci template

[Jake-Shadle]

• Update checkout to v2, which is strictly better than v1
• Update cargo-deny to v1
• Improve on event trigger, the current [push, pull_request] actually runs all CI jobs twice on PRs, this one only runs CI once on PRs, pushes to main, and on any tags (eg when doing a release)

[lpil]

What do you think of any removing the use of the cargo action? It actually recommends using run: cargo test etc unless you're using its extra features, which we're not from what I can see.

It's more concise and means we have one less action to download.

[Jake-Shadle]

That's true, we would miss out on Warnings and errors issued by cargo will be displayed in GitHub UI, but then again, cargo's output is easily readable in the log anyways, that feature is just extra sugar. I'll just remove it.

[lpil]

Oh! That seems like a good though reason to keep it if people find it handy. I didn't realise that.

[Jake-Shadle]

I actually never use it and just go directly to the logs tbh.