add http timeout options

README.md

@@ -167,7 +167,10 @@ post "/push" do
       subject: "mailto:[email protected]",
       public_key: ENV['VAPID_PUBLIC_KEY'],
       private_key: ENV['VAPID_PRIVATE_KEY']
-    }
+    },
+    ssl_timeout: 5, # value for Net::HTTP#ssl_timeout=, optional
+    open_timeout: 5, # value for Net::HTTP#open_timeout=, optional
+    read_timeout: 5 # value for Net::HTTP#read_timeout=, optional
   )
 end
 ```

lib/webpush/request.rb

@@ -18,6 +18,10 @@ def initialize(message: "", subscription:, vapid:, **options)
     def perform
       http = Net::HTTP.new(uri.host, uri.port)
       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?
+      http.read_timeout = @options[:read_timeout] unless @options[:read_timeout].nil?
+
       req = Net::HTTP::Post.new(uri.request_uri, headers)
       req.body = body
       resp = http.request(req)