Update Rust compiler options with "Rust 1.66.0 (2021)"

[davidmcnamee]

Hi, I just noticed the VSCode extension wasn't working for Rust submissions to Codeforces... I think it's because Codeforces uses a newer Rust compiler than what the extension currently supports. This is my first PR, so let me know if there's anything else you'd like me to change/test, or if there's a better way to get this patch upstream.

I took the ID from this page, where I found this in the raw html:
<option value="75" selected="selected">Rust 1.66.0 (2021)</option>. The previous rust compiler ("Rust 1.42.0") is no longer an option on the Codeforces site.

Testing

tested by running vsce package and installing locally. It submitted this Rust program successfully:

Also the automated tests seem to pass:

$ npm run test

> competitive-programming-helper@5.9.2 pretest
> tsc -p ./


> competitive-programming-helper@5.9.2 test
> jest out/

 PASS  out/tests/utilsPure.test.js
 PASS  out/tests/judge.test.js

Test Suites: 2 passed, 2 total
Tests:       7 passed, 7 total
Snapshots:   0 total
Time:        1.095 s

[davidmcnamee]

I was a bit too quick to open this PR; here's an issue that describes the bug #316

[agrawal-d]

Thanks! LGTM!