fix(http): fix check logic to decide whether to set `Origin` header (#1438)

ref: https://github.com/tauri-apps/plugins-workspace/issues/1389#issuecomment-2150470335

.changes/http-origin-duplicated.md

@@ -0,0 +1,5 @@
+---
+"http": "patch"
+---
+
+Fix `ORIGIN` header containing 2 URLs when `unsafe-headers` feature flag is enabled.

plugins/http/src/commands.rs

@@ -224,8 +224,8 @@ pub async fn fetch<R: Runtime>(
                     request = request.header(header::USER_AGENT, "tauri-plugin-http");
                 }
 
-                if !(cfg!(feature = "unsafe-headers")
+                if cfg!(feature = "unsafe-headers")
-                    && headers.contains_key(header::ORIGIN.as_str()))
+                    && !headers.contains_key(header::ORIGIN.as_str())
                 {
                     if let Ok(url) = webview.url() {
                         request =