Change internal state of Badger2040 to protected

libraries/badger2040/badger2040.hpp

@@ -9,7 +9,7 @@
 namespace pimoroni {
 
   class Badger2040 {
-  private:
+  protected:
     UC8151 uc8151;
     const hershey_font_t *_font = &futural;
     uint8_t _pen = 0;
@@ -96,4 +96,4 @@ namespace pimoroni {
 
   };
 
-}
+}