fix: https.passphrase option should be respected

serverUtils.getHttpsOptions() was ignoring the `https.passphrase` options since the "default" https options were merged on top of user options. Another solution to this is to just omit the `passphrase` key entirely in the defaults section, but I took this approach in order to preserve the current behavior where it's set to an empty string by default.

Author: David Zukowski

packages/browser-sync/lib/server/utils.js

@@ -54,7 +54,7 @@ function getHttpsServerDefaults(options) {
         key: getKey(options),
         cert: getCert(options),
         ca: getCa(options),
-        passphrase: ""
+        passphrase: options.getIn(["https", "passphrase"], "")
     });
 }