Doc req updates

[alegresor]

• consolidate dependencies to a single environment.yml file compatible across all platforms with Python 3.9
• update GitHub Actions and ReadTheDocs to compile based on new environment.yml file
• note that we remove LatNet Builder from the developer environment in order to use Python 3.9. When LatNet Builder updates to support Python >= 3.9 we will add it back

[sou-cheng-choi]

Dear Aleksei, I have tested on Mac M1. After setting up a new virtual environment with the much cleaner environment.yml, all tests passed. For the make targets such as "doc_html", I got the following error message:

# Make Directries
# READMEs --> RST
make: pandoc: No such file or directory
make: *** [_doc] Error 1

So I proceeded to install pandoc by "conda install -c conda-forge pandoc"; the installed version is 2.2. Afterward, all documentation generation tasks became successful.

Also need to update "makefile" to remove mentions of folder "requirements" and "dev*.txt" since they no longer exist.

I have made a commit with the above changes and now make tests and make doc_* succeed on my machine:

https://github.com/QMCSoftware/QMCSoftware/commit/7d8238fa1df143a252d8a2d454beb7909b9a58fc

[codecov]

Codecov Report

Merging #293 (7d8238f) into develop (8765a32) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop     #293   +/-   ##
========================================
  Coverage    88.06%   88.06%           
========================================
  Files           87       87           
  Lines         4206     4206           
========================================
  Hits          3704     3704           
  Misses         502      502           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8765a32...7d8238f. Read the comment docs.