Update sketch.ino

Fixed error when comliling with debug:
FHEMduino.ino: In function 'bool receiveProtocolKW9010(unsigned int)':
FHEMduino:886: error: conflicting declaration 'String bitmessage'
FHEMduino:873: error: 'bitmessage' has a previous declaration as 'bool bitmessage [36]'