Use `chromium` package to run karma tests

package.json

@@ -37,6 +37,7 @@
     "@types/chai": "^4.2.14",
     "@types/mocha": "^8.0.3",
     "chai": "^4.2.0",
+    "chromium": "^3.0.3",
     "eslint": "^7.12.0",
     "eslint-plugin-github": "^4.1.1",
     "karma": "^5.2.3",

test/karma.config.cjs

@@ -1,4 +1,7 @@
 const resolve = require('@rollup/plugin-node-resolve').default
+
+process.env.CHROME_BIN = require('chromium').path
+
 module.exports = function (config) {
   config.set({
     basePath: '..',