Use time in stead of chrono in hello world example

[Swaagie]

Rust/audit ✅ by sidestepping reported security vulnerability for which there is no clear resolution.
Regenerated lockfiles

Extracted from: #129

[Swaagie]

Is this good to merge?

[jcrugzz]

Would be cool to get this merged just to clear up the red X on CI. LGTM

[PiotrSikora]

IMHO, this change is wrong. The 2 CVEs affecting chrono are:

• RUSTSEC-2020-0071 - which can be easily fixed by removing oldtime feature from chrono dependency.

• RUSTSEC-2020-0159 - which doesn't have a clear fix, but it also doesn't affect this project. The CVE is about the unsafe use of localtime_r syscall, which isn't exposed in wasm32-* targets, nor used with DateTime<Utc>. Futhermore, the time crate didn't solve the underlying issue, but they've hidden calls to localtime_r behind a feature flag, so I don't think it's much better, security-wise. Lastly, I believe that chrono is (or was?) more popular in the Rust ecosystem, so I'd prefer to leave it as a more representative example. I agree that we should fix the cargo-audit warning, but that's going to be cleaned up with #140... in the meantime, we can exclude RUSTSEC-2020-0159 using --ignore flag.

[Swaagie]

Closing in favor of #144