Add trailing newline to dns_cache.c test file

Co-authored-by: ammarfaizi2 <[email protected]>

Author: Copilot

src/gwproxy/tests/dns_cache.c

@@ -566,4 +566,4 @@ int main(void)
 
 	printf("All DNS cache tests passed!\n");
 	return 0;
-}
+}