Update src/literals.h

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: mathieucarbou

src/literals.h

@@ -24,8 +24,13 @@
 
 namespace asyncsrv {
 
+#ifdef ARDUINO  
+using ::emptyString;  
+#else  
+inline const String emptyString{};  
+#endif  
+
 static constexpr const char empty[] = "";
-static const String emptyString;
 
 static constexpr const char T__opaque[] = "\", opaque=\"";
 static constexpr const char T_100_CONTINUE[] = "100-continue";