MangaCoverFetcher: Use source's header for network request (#6847)

app/src/main/java/eu/kanade/tachiyomi/data/coil/MangaCoverFetcher.kt

@@ -141,7 +141,7 @@ class MangaCoverFetcher(
     private fun newRequest(): Request {
         val request = Request.Builder()
             .url(url)
-            .headers(options.headers)
+            .headers(sourceLazy.value?.headers ?: options.headers)
             // Support attaching custom data to the network request.
             .tag(Parameters::class.java, options.parameters)