Switch from HEAD to GET for latency measurement

Hetzner speed test servers drop the connection on HEAD requests,
causing fetch to throw a network error. GET works universally and
with no-cors mode the response is opaque anyway.

src/main.js

@@ -125,7 +125,7 @@ async function detectGateway() {
                 const timeoutId = setTimeout(() => controller.abort(), 1500);
                 try {
                     await fetch(url, {
-                        method: "HEAD",
+                        method: "GET",
                         mode: "no-cors",
                         cache: "no-store",
                         signal: controller.signal,
@@ -240,7 +240,7 @@ async function measureLatency(url) {
 
     try {
         await fetch(targetUrl.toString(), {
-            method: "HEAD",
+            method: "GET",
             mode: "no-cors",
             cache: "no-store",
             signal: controller.signal,