regression test for specifying channel name in enviornment.yml dependency

this didn't work with mamba 0.5

Author: minrk

tests/conda/channel-dep/environment.yml

@@ -0,0 +1,6 @@
+name: lume-model-server-demo
+dependencies:
+  - python=3.7
+  # specify a channel name in the dependency
+  # mamba < 0.6 doesn't handle this right
+  - bokeh::jupyter_bokeh==2.0.3

tests/conda/channel-dep/verify

@@ -0,0 +1,2 @@
+#!/usr/bin/env python3
+import jupyter_bokeh