Add User-Agent to news page HTTP requests

Cloudflare, and some other MITM proxies consider the default Java HttpURLConnection
from Java 1.8 to be an invalid, unsafe request and reject it. This leads to CF returning a
403 on request. This commit adds the same User-Agent that's applied to the other calls, so
that those that front their SKMC launcher news page with Cloudflare can have successful
page loads.

launcher/src/main/java/com/skcraft/launcher/swing/WebpagePanel.java

@@ -250,6 +250,7 @@ public final class WebpagePanel extends JPanel {
                 conn = (HttpURLConnection) url.openConnection();
                 conn.setRequestMethod("GET");
                 conn.setUseCaches(false);
+                conn.setRequestProperty("User-Agent", "Mozilla/5.0 (Java) SKMCLauncher");
                 conn.setDoInput(true);
                 conn.setDoOutput(false);
                 conn.setReadTimeout(5000);