build: inline pkg version

[P0lip]

Fixes #[ISSUE_NUMBER].

Checklist

• Tests added / updated
• Docs added / updated
• Check this off Breaking change?

Does this PR introduce a breaking change?

• Yes
• No

😱

Let me explain...
In a browser environment without access to any kind of fs, Spectral will try to obtain rulesets from npm. This approach is fairly fine, but comes with a downside - you cannot change the location of rulesets if you don't want to break Spectral for users. This PR addresses this issue thanks to specifying the actual version of a given release.
I didn't want to rely on package.json on purpose - it would require require 😆 or imports and so on. You know. The solution proposed here should, in theory, be more reliable.

[billiegoose]

I..... I know using AST is your style, but... wouldn't something like this be more robust and easier to maintain?

#! /usr/bin/env node
var pkg = require('../../package.json')
var replace = require('replace-in-file')
var options = {
  files: ['src/**/*.ts'],
  from: /INJECT_SPECTRAL_VERSION_HERE/g,
  to: pkg.version
}
;(async function () {
  await replace(options)
})()

[P0lip]

@wmhilton
As you know, I am not a fan of modifying a code via replace.
You know, If we needed to inject the code in multiple places, I'd likely use such a replace or write a more robust solution relying on AST modifications, but hm. It just this particular place for now.
If we happen to find a need for supporting more places, we can easily throw some walker in and make a modification on every matching string.

[P0lip]

We are short on time, therefore I am going to merging the PR now, but we can always revert this in future or revisit the approach.
I'm up to the discussion, just leave a comment here.