Correctly initialise WebPush connection (#2417)

The `ipaddr` arg here is being interpreted as a positional arg (since
the keyword arg doesn't exist), which results in an invalid connection
object. This was causing push notifications to silently fail.

We should initialise the property on the object instead.

config/initializers/web_push.rb

@@ -20,7 +20,8 @@ module WebPush::PersistentRequest
     endpoint_ip = @options[:endpoint_ip]
 
     if endpoint_ip
-      http = Net::HTTP.new(uri.host, uri.port, ipaddr: endpoint_ip)
+      http = Net::HTTP.new(uri.host, uri.port)
+      http.ipaddr = endpoint_ip
       http.use_ssl = true
       http.ssl_timeout = @options[:ssl_timeout] unless @options[:ssl_timeout].nil?
       http.open_timeout = @options[:open_timeout] unless @options[:open_timeout].nil?