Update libraries/Arduino_CAN/src/R7FA4M1_CAN.h

Co-authored-by: Alexander Entinger <consulting@lxrobotics.com>

Author: Woodwarth

libraries/Arduino_CAN/src/R7FA4M1_CAN.h

@@ -54,7 +54,7 @@ class R7FA4M1_CAN final : public HardwareCAN
   bool begin(CanBitRate const can_bitrate) override;
   void end() override;
 
-  void setMailboxMask(int mailbox_group,uint32_t mask);
+  void setMailboxMask(size_t const mailbox_group,uint32_t const mask);
   void setMailboxID(int mailbox,int id);
 
   int enableInternalLoopback();