upm: bump mraa requirement to 0.7.6 for java bindings
upm: bump mraa requirement to 0.7.6 for java bindings

Signed-off-by: Mihai Tudor Panu <a27de6130c5d32f5817bf40bb8b348582f37a8af@intel.com>

Vaghesh/upm,Vaghesh/upm,Vaghesh/upm,Vaghesh/upm