docker and doc fix-ups

[silverjam]

Description

• numpy is technically needed for the fftmonitor, but since that's the only thing that uses it I think we've intentionally omitted it from our dependency list... this breaks the documentation generator though, since it tries import the package-- previously this was installed via the generator (somehow) -- now we're explicitly installing the dependency in the tox.ini command that's used to run the documentation generator

• Don't run autoremove in the dockerfile, this seems to be uninstalling enchant or something else that the pyenchant package needs

• Fix Sphinx config error seen in recent release:

 sphinx-build -b spelling -d build/doctrees  -W source build/spelling
Running Sphinx v5.0.1
Warning, treated as error:
Invalid configuration value found: 'language = None'. Update your configuration to a valid langauge code. Falling back to 'en' (English).
Creating file ./sbp.rst.
Creating file ./sbp.acquisition.rst.
Creating file ./sbp.bootload.rst.

API compatibility

N/A

[fpezzinosn]

I had the same error where one of the constructs test kept failing. This is the fix I found #1156 (comment)

[silverjam]

I had the same error where one of the constructs test kept failing. This is the fix I found #1156 (comment)

I haven't had issues with the parallel tests fairly so frequently until now... I may have to undo the work I did to attempt to run them in parallel...

[silverjam]

Force merging since this has to do with stability of the build