improvement: upgrade query-string to v8

There already is a version 8.1 of the query-string library, but since
8.0 the library is a pure ESM package. To be able to use v8+, we have to
convert our libraries to become ESM packages as well.

Made changes following
https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c to
make this library an ESM package.

Closes #70

.eslintrc.json

@@ -0,0 +1,21 @@
+{
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "ecmaVersion": 2018,
+    "sourceType": "module"
+  },
+  "extends": ["plugin:@typescript-eslint/recommended"],
+  "plugins": ["@typescript-eslint", "jest"],
+  "rules": {
+    "indent": "off",
+    "@typescript-eslint/indent": ["error", 2],
+    "@typescript-eslint/no-use-before-define": ["off"],
+    "@typescript-eslint/no-explicit-any": ["off"],
+    "@typescript-eslint/no-use-before-define": ["off"],
+    "@typescript-eslint/explicit-member-accessibility": ["off"],
+    "jest/prefer-expect-assertions": [
+      "error",
+      { "onlyFunctionsWithAsyncKeyword": true }
+    ]
+  }
+}