Replace fast-glob with a lighter tinyglobby (#165)

* Replace `fast-glob` with `tinyglobby`

`tinyglobby` uses `picomatch` under the hood which default to
case-sensitive matching. Not sure what are the performance
implications of performing such matching on Unix systems, but in case
we want to preserve the distinction, an update in `tinyglobby` would be
needed to expose the underlying `picomatch` options or add a new
top-level one that'd control the `nocase` flag.

* Update the README after changing the glob provider

* Remove `packageManager` from `package.json`

* Reorder the import

* Bump `tinyglobby`

* Fix test failures in CI and on Windows

* Always match case-insensitively

* Remove `packageManager` again (sorry)

README.md

@@ -351,7 +351,7 @@ module.exports = {
 Type: `string|string[]`
 
 Similar to [`mixinsDir`](#mixinsdir); except, you can provide
-[fast-glob](https://github.com/mrmlnc/fast-glob) syntax to target or not target
+[tinyglobby](https://github.com/SuperchupuDev/tinyglobby) syntax to target or not target
 specific files.
 
 ```js

index.js

@@ -1,13 +1,11 @@
-let glob = require('fast-glob')
 let { readFileSync } = require('node:fs')
-let { platform } = require('node:os')
 let { basename, extname, join, relative } = require('node:path')
 let { parse } = require('postcss-js')
 let vars = require('postcss-simple-vars')
 let sugarss = require('sugarss')
+let { globSync } = require('tinyglobby')
 
 let MIXINS_GLOB = '*.{js,cjs,mjs,json,css,sss,pcss}'
-let IS_WIN = platform().includes('win32')
 
 function addMixin(helpers, mixins, rule, file) {
   let name = rule.params.split(/\s/, 1)[0]
@@ -48,7 +46,7 @@ function processModulesForHotReloadRecursively(module, helpers) {
 
 function loadGlobalMixin(helpers, globs) {
   let cwd = process.cwd()
-  let files = glob.sync(globs, { caseSensitiveMatch: IS_WIN })
+  let files = globSync(globs, { caseSensitiveMatch: false })
   let mixins = {}
   files.forEach(i => {
     let ext = extname(i).toLowerCase()

package.json

@@ -35,10 +35,10 @@
     "postcss": "^8.2.14"
   },
   "dependencies": {
-    "fast-glob": "^3.3.2",
     "postcss-js": "^4.0.1",
     "postcss-simple-vars": "^7.0.1",
-    "sugarss": "^4.0.1"
+    "sugarss": "^4.0.1",
+    "tinyglobby": "^0.2.6"
   },
   "devDependencies": {
     "@logux/eslint-config": "^53.4.0",