Prepare pycparser for secp256k1
Prepare pycparser for secp256k1

During installation of secp256k1 the pycparser version of the
requirements.tx is not respected.

charles-cooper/raiden,hackaugusto/raiden,tomaaron/raiden,tomashaber/raiden,charles-cooper/raiden,tomashaber/raiden,tomaaron/raiden,tomaaron/raiden,tomashaber/raiden,tomaaron/raiden,tomashaber/raiden,tomashaber/raiden,hackaugusto/raiden