Update SSDP source port to 3339

Author: alexballas

README.md

@@ -95,7 +95,7 @@ Go2TV also supports selecting subtitles for video files that have embedded subti
 
 **SSDP Listen Port Range (for firewall configurations)**
 
-Go2TV now binds the SSDP listener to a port within the fixed range 1900-2000, instead of relying on the system's automatic port assignment. The application will automatically select the first available port from this range. If you are running Go2TV behind a firewall, ensure that inbound UDP traffic is allowed on ports 1900-2000 to enable proper SSDP discovery and device communication.
+Go2TV now binds the SSDP listener to a port within the fixed range 3339-3438, instead of relying on the system's automatic port assignment. The application will automatically select the first available port from this range. If you are running Go2TV behind a firewall, ensure that inbound UDP traffic is allowed on ports 3339-3438 to enable proper SSDP discovery and device communication.
 
 **MacOS potential issues**
 

assets/linux/app.go2tv.go2tv.appdata.xml

@@ -57,6 +57,7 @@
             <li>Resolved FFmpeg video scaling issues.</li>
             <li>Increased size of the subtitles when transcoding.</li>
             <li>Added new translations for Chinese.</li>
+            <li>Improved device discoverability: the app now uses source ports 3339-3438 for SSDP discoverability.</li>
           </ul>
         </description>
         <url type="details">https://github.com/alexballas/go2tv/releases/tag/v1.19.0</url>

devices/devices.go

@@ -23,7 +23,7 @@ func LoadSSDPservices(delay int) (map[string]string, error) {
 	// Reset device list every time we call this.
 	urlList := make(map[string]string)
 
-	port := 1900
+	port := 3339
 
 	var (
 		address *net.UDPAddr