make docs isn't working.

[DailyDreaming]

Might need to upgrade sphinx (currently 2.1.2 -> 3.0.x).

(v3nv) quokka@qcore:~/git/delet/dcp-cli$ make docs
make -C docs html
make[1]: Entering directory '/home/quokka/git/delet/dcp-cli/docs'
Running Sphinx v2.1.2
making output directory... done
building [mo]: targets for 0 po files that are out of date
building [html]: targets for 3 source files that are out of date
updating environment: 3 added, 0 changed, 0 removed
reading sources... [ 33%] api                                                   
Exception occurred:
  File "/usr/lib/python3.6/inspect.py", line 186, in iscoroutinefunction
    object.__code__.co_flags & CO_COROUTINE)
AttributeError: '_ClientMethodFactory' object has no attribute '__code__'
The full traceback has been saved in /tmp/sphinx-err-6jwazei4.log, if you want to report the issue to the developers.
Please also report this if it was a user error, so that a better error message can be provided next time.
A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!
Makefile:20: recipe for target 'html' failed
make[1]: *** [html] Error 2
make[1]: Leaving directory '/home/quokka/git/delet/dcp-cli/docs'
Makefile:47: recipe for target 'docs' failed
make: *** [docs] Error 2

[jeffrey856]

Closed by this fix from sphinx.

sphinx-doc/sphinx#6605