base64 class uses String, adding harmless #include (#7517)

d-a-v · web-flow · commit 6feda9ebda8d · 2020-08-11T14:30:39.000+02:00
diff --git a/cores/esp8266/base64.h b/cores/esp8266/base64.h
@@ -25,6 +25,8 @@
 #ifndef CORE_BASE64_H_
 #define CORE_BASE64_H_
 
+#include <WString.h>
+
 class base64
 {
 public:
