Build issue after arm none eabi gcc update

[fpistm]

Hi,

I've updated the arm none eabi gcc toolchain used by the STM32 core to the v9.2.1.
I've built all Arduino built-in example without any issue except those for Firmata, see the error hereafter:

Firmata/Firmata.h:131:17: error: friend declaration of 'void encodeByteStream(size_t, uint8_t*, size_t) const' specifies default arguments and isn't a definition [-fpermissive]
  131 |     friend void FirmataMarshaller::encodeByteStream (size_t bytec, uint8_t * bytev, size_t max_bytes = 0) const;
      |                 ^~~~~~~~~~~~~~~~~

As specified by the compiler output, error comes from the default argument here:

arduino/Firmata.h

Line 131 in 1ccb2c0

friend void FirmataMarshaller::encodeByteStream (size_t bytec, uint8_t * bytev, size_t max_bytes = 0) const;

As it is also specified here:

arduino/FirmataMarshaller.h

Line 67 in 1ccb2c0

void encodeByteStream (size_t bytec, uint8_t * bytev, size_t max_bytes = 0) const;

I guess it could be removed from the friend declaration as already declare in FirmataMarshaller.h

Ref:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2000/n1263.html