Upgrade deps as of 2021-04-24 (#590)

* Bump discord.js to 12.5.3

* Bump commander to ^7.2.0

* Bump simple-markdown to ^0.7.3

* Bump @babel dependencies to ^7.13

* Bump cross-env to ^7.0.3

(Nothing relevant; just went to maintenance-only mode)

* Bump lodash to ^4.17.21

* Bump eslint dependencies

* Bump test dependencies (chai, mocha, sinon, sinon-chai)

* Replace babel-eslint with @babel/eslint-parser

* Bump sub-dependencies

.eslintrc

@@ -1,6 +1,6 @@
 {
   "extends": "airbnb-base",
-  "parser": "babel-eslint",
+  "parser": "@babel/eslint-parser",
   "env": {
     "mocha": true,
     "node": true

lib/cli.js

@@ -31,8 +31,10 @@ function run() {
     )
     .parse(process.argv);
 
+  const opts = program.opts();
+
   // If no config option is given, try to use the env variable:
-  if (program.config) process.env.CONFIG_FILE = program.config;
+  if (opts.config) process.env.CONFIG_FILE = opts.config;
   if (!process.env.CONFIG_FILE) throw new Error('Missing environment variable CONFIG_FILE');
 
   const completePath = path.resolve(process.cwd(), process.env.CONFIG_FILE);