ci: delete conda/channel-dep test of a mamba 0.6+ feature (~5 min saved)

tests/conda/channel-dep/environment.yml

@@ -1,6 +0,0 @@
-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

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