Reduced cachebust fingerprint to be more reasonable

[orlp]

Using a full 256-bit hash for cachebusting is complete overkill (and a waste of pagesize bytes). It isn't for security, simply to invalidate the browser cache if the file changes.

I've changed it to 80 bits. Since you'll see on average a collision from a collection of n elements after sqrt(n) random samples, this means you'd have to do 2^40 edits on the same file, with the browser caching all of them, before you would load a stale version. That is, even if you edited your CSS file every second and cached all of them for eternity it would still take you ~34865 years before seeing a collision. I think that's plenty.

So instead of this:

<link rel="stylesheet" href="/assets/style.css?h=23d9476e2b2eb5b846066019f1ffecec1be0e80ce171161175b5441699b24ccf">

You would see:

<link rel="stylesheet" href="/assets/style.css?h=23d9476e2b2eb5b84606">

[orlp]

Locally the tests pass, so not sure what the CI is up to.

[Keats]

There is a hardcoded fingerprint in the can_cachebust_static_files test

[orlp]

...I made a line less long and now the cargo fmt CI starts complaining? I can't be bothered with this.

[c-git]

Yeah because now it should be part of the line above. It is not long enough to warrant a separate line

[Keats]

Don't worry about the CI failure, I'll fmt it later