Replace deprecated URL parser

Fix up various linter errors

lib/agent.js

@@ -20,15 +20,18 @@ function env (key) {
 
 module.exports = function () {
   try {
-    const proxy = url.parse(proxies.map(env).find(is.string));
+    const proxy = new url.URL(proxies.map(env).find(is.string));
     const tunnel = proxy.protocol === 'https:'
       ? tunnelAgent.httpsOverHttps
       : tunnelAgent.httpsOverHttp;
+    const proxyAuth = proxy.username && proxy.password
+      ? `${proxy.username}:${proxy.password}`
+      : null;
     return tunnel({
       proxy: {
         port: Number(proxy.port),
         host: proxy.hostname,
-        proxyAuth: proxy.auth
+        proxyAuth
       }
     });
   } catch (err) {

lib/output.js

@@ -517,7 +517,7 @@ const formats = new Map([
 function toFormat (format, options) {
   const actualFormat = formats.get(is.object(format) && is.string(format.id) ? format.id : format);
   if (!actualFormat) {
-    throw is.invalidParameterError('format', `one of: ${[...formats.keys()].join(`, `)}`, format);
+    throw is.invalidParameterError('format', `one of: ${[...formats.keys()].join(', ')}`, format);
   }
   return this[actualFormat](options);
 }