Add LatestReleases variant to Conda jobs

[traversaro]

This is useful in general, but useful in particular to debug #712, as the build seems to be working fine on Unstable (that use yarp master branch) and in the Conda package generation (that use yarp released version 3.4.3). This job would help clarify if the problem is in the commit on top of 3.4.3 in yarp-3.4 branch, or somewhere else.

[traversaro]

Unfortunately LatestRelease on Windows is failing for another error, in particular:

2021-05-12T17:56:40.2920163Z   -- Found Python3: C:/Miniconda/envs/test/python.exe (found version "3.9.4") found components: Interpreter Development Development.Module Development.Embed 
2021-05-12T17:56:40.2927372Z   CMake Error at bindings/python/CMakeLists.txt:17 (get_filename_component):
2021-05-12T17:56:40.2928355Z     get_filename_component called with incorrect number of arguments
2021-05-12T17:56:40.2928991Z   
2021-05-12T17:56:40.2929408Z   
2021-05-12T17:56:40.2959706Z   -- Configuring incomplete, errors occurred!

This is due to robotology/yarp#2527 not being released. While we could fix this with a workaround, if we do not that, this is blocking for #641 .

[traversaro]

Closing for now.