Add eslint-plugin-regexp

This change is created by:
- the `npm i eslint-plugin-regexp` command
- a few additions to the `.eslintrc.js` file.

Close #141

.eslintrc.js

@@ -15,6 +15,7 @@ module.exports = {
     "plugin:node/recommended",
     "plugin:jest/recommended",
     "plugin:jest/style",
+    "plugin:regexp/recommended",
     "prettier",
   ],
   rules: {
@@ -113,5 +114,8 @@ module.exports = {
     "prefer-template": "error",
     "sort-requires/sort-requires": "error",
     strict: ["error", "global"],
+
+    // Prefer code readability over a bit performance improvement.
+    "regexp/no-unused-capturing-group": "off",
   },
 };

package.json

@@ -29,6 +29,7 @@
     "eslint-plugin-eslint-comments": "^3.2.0",
     "eslint-plugin-jest": "^24.3.6",
     "eslint-plugin-node": "^11.1.0",
+    "eslint-plugin-regexp": "^1.1.0",
     "eslint-plugin-sort-requires": "^2.1.0"
   },
   "publishConfig": {