Modernize SVGO setup (#8149)

* SVGO now discovers config file automatically

* Drop `svgo` script from package.json

* Use '.mjs' extension for SVGO config file

CONTRIBUTING.md

@@ -144,9 +144,7 @@ If you have any problems or questions while creating the SVG, check out [the Git
 All icons in Simple Icons have been optimized with the [SVGO tool](https://github.com/svg/svgo). This can be done in one of three ways:
 
 * The [SVGO Command Line Tool](https://github.com/svg/svgo)
-  * Install dependencies
-    * With npm: `npm install` from the root of this repository
-  * Run the following command `npm run svgo -- icons/file-to-optimize.svg`
+  * Run the following command `npx svgo icons/file-to-optimize.svg`
   * Check if there is a loss of quality in the output, if so increase the precision.
 * The [SVGOMG Online Tool](https://jakearchibald.github.io/svgomg/)
   * Click "Open SVG" and select an SVG file.

package.json

@@ -73,7 +73,6 @@
     "test": "mocha tests --reporter tests/min-reporter.cjs --inline-diffs",
     "pretest": "npm run prepublishOnly",
     "posttest": "npm run postpublish",
-    "svgo": "svgo --config svgo.config.js",
     "get-filename": "node scripts/get-filename.js",
     "add-icon-data": "node scripts/add-icon-data.js"
   },

svgo.config.mjs

@@ -1,4 +1,4 @@
-module.exports = {
+export default {
   multipass: true,
   eol: 'lf',
   plugins: [