CAS-13883: casadocs task and tool pages: parameter (multi)types are broken in releases >=6.4.0

[FedeMPouzols]

PR for https://open-jira.nrao.edu/browse/CAS-13883

[FedeMPouzols]

The build of this branch (I just merged master before opening the PR) failed, and the 'latest' build started failing yesterday: https://readthedocs.org/projects/casadocs/builds/
There seems to be some pandoc problem, but the error messages look vaguely familiar or similar to the errors we were getting when the casa6 repo was not public (around a couple of weeks ago).

[FedeMPouzols]

The issue in recent builds of casadocs comes from pypandoc (download_pandoc() function), which has stopped working after github updated its release download pages. Issue: JessicaTegner/pypandoc#295, fix being worked on: JessicaTegner/pypandoc#296

Once there is a release of pypandoc with this fix, casadocs should update its requirements.txt to use it.

[bemonts]

Thanks @FedeMPouzols for figuring out the problem. Do you know where we can track the status for release of pypandoc with fix?

[smcastro]

Thanks Federico. The changes look good to me, although it would be better to wait for the build to be fixed to see the rendered pages.

[FedeMPouzols]

Yes, the pypandoc fix is for now in this PR to the pypandoc repo: JessicaTegner/pypandoc#296

[FedeMPouzols]

@bemonts , @smcastro : I've merged master into this branch and the casadocs buildfrom this branch has now passed. The rendered docs look good to me.

(With this temporary change to hardcode the url to download pandoc: 3f98ee7 the 'latest' builds are working now)

After the upcoming CASA release and/or depending when the updated pypandoc release becomes available we have to remember to remove the hardcoded url and use again a proper version tag (assuming the upgrade of pypandoc to the latest release is harmless, which I would expect). I'd suggest we create at least an issue in this repo to keep track of that.

[FedeMPouzols]

Merging this branch for 6.5.2.

As discussed in the chat, after this temporari fix: 3f98ee7, the casadocs builds are working again. After merging master with that update into this branch the docs were rendered again and they looked fine.

[bemonts]

Thanks, @FedeMPouzols !!