[dev.yml] Fix all the beat dependencies to match the versions used by buildout

Since beat.core is fixed at 1.8.0, the others must also
be pinned to their corresponding versions.

See release.cfg

dev.yml

@@ -4,13 +4,19 @@ channels:
   - http://www.idiap.ch/software/beat/conda
   - defaults
 dependencies:
+  - pip
+
   # packages you may pin are here
   - python=3.6
   - bob-devel=2019.08.28
   - beat-devel=2019.08.28
 
-  # requirements.txt, they are indirectly pinned through the above
+  # beat dependencies matching release.cfg
   - beat.core=1.8
+  - beat.backend.python=1.6.2
+  - beat.cmdline=1.4.1
+
+  # requirements.txt, they are indirectly pinned through the above
   - docopt
   - docutils
   - jinja2
@@ -21,7 +27,6 @@ dependencies:
   - simplejson
 
   # these are required for local development, they are not runtime
-  - beat.cmdline
   - bob.extension
   - nose
   - coverage