CI constant fail on lenet.ipynb

[roywei]

Error msg:

[NbConvertApp] Converting notebook chapter_convolutional-neural-networks/lenet.ipynb to html
Nov 16, 2020 7:31:39 PM io.github.spencerpark.jupyter.channels.Loop start
INFO: Loop starting...
Nov 16, 2020 7:31:39 PM io.github.spencerpark.jupyter.channels.Loop start
INFO: Loop started.
Nov 16, 2020 7:31:39 PM io.github.spencerpark.jupyter.channels.Loop start
INFO: Loop starting...
Nov 16, 2020 7:31:39 PM io.github.spencerpark.jupyter.channels.Loop start
INFO: Loop started.
Nov 16, 2020 7:31:39 PM io.github.spencerpark.jupyter.channels.Loop start
INFO: Loop starting...
Nov 16, 2020 7:31:39 PM io.github.spencerpark.jupyter.channels.Loop start
INFO: Loop started.
[NbConvertApp] Executing notebook with kernel: java
Nov 16, 2020 7:33:16 PM io.github.spencerpark.ijava.JavaKernel formatError
WARNING: 
jdk.jshell.EvalException: MXNet engine call failed: MXNetError: Check failed: ctx.dev_mask() == Context: :kGPU (-1073741696 vs. 2) : 
Stack trace:
  File "src/resource.cc", line 138