fix: Add small startup delay to fix connection failures

If the external driver binary doesn't start listening quickly enough, it's
possible for the client to connection too soon and have its connection refused.
This adds a brief (2s) delay before connecting, to give the external driver
time to start up.  This happens to be enough time on my Mac, on which the
drivers happen to start slowly enough for this issue to occur in the first
place.

index.js

@@ -97,7 +97,9 @@ const LocalWebDriverBase = function(
     log.debug('[http] ' + meth + ' ' + path + ' ' + (data || ''));
   });
 
-  this.on('start', (url) => {
+  this.on('start', async (url) => {
+    await new Promise((resolve) => setTimeout(resolve, 2000));
+
     this.browser.init(this.spec, (error) => {
       if (error) {
         log.error(`Could not connect to ${this.browserName} WebDriver`);