Add a CI test against another kernel

[blink1073]

Problem

We are currently only testing against ipykernel. If we were testing against at least one other kernel we can be more confident that our changes are not adversely affecting other kernels.

Proposed Solution

Add a CI job that installs IRKernel in a conda environment and runs a test that launches IRKernel and executes code. What we could do is run test_irkernel.py using a local checkout of jupyter_kernel_test, which we are currently doing only for test_ipykernel.py.

Additional context

Use jupyter_kernel_test as an example for the CI setup.

[davidbrochart]

+1
What about also testing IJulia?

[blink1073]

Good point, I was able to set it up pretty quickly locally:

• Create conda env with julia and jupyterlab
• Run julia -e 'using Pkg; Pkg.add("IJulia")'
• Run jupyterlab and launch Julia kernel