Add `enum34` and `future` find modules
Add find modules for enum34
and future
from LCG. The latter is also
required by tdaq-common-03-00-00. Add this dependency to its find
module.
With this we can then remove the enum34
module from AtlasPyFwdBwdPorts. I do wonder if we should be adding some generic "find LCG python package" module as there is quite a lot of copy&paste happening here.
Tested with "TestExternals" by adding find_package( abc REQUIRED )