update the 'tested proton version' check prior to release

When building against the Proton master / 0.16.0 RC, the qpid-cpp master currently logs out:

-- Found Proton: <install-path>/lib64/libqpid-proton.so (found version "0.16.0")
CMake Warning at src/amqp.cmake:28 (message):
  Qpid proton 0.16.0 is not a tested version and might not be compatible,
  0.14 is highest tested; build may not work

That is because 0.14 was the latest available when qpid-cpp 1.35.0 went out. We should update this check for 1.36.0 so that using it with Proton 0.16.0 does not generate a warning.