chore(docker): drop support for PyPy

[jansegre]

Motivation

We've had some partial support for PyPy that never took off, there are no known cases using PyPy for either production or even experimenting. Although our initial tests a long time ago have shown significant performance improvements over the best Python version at the time, it never ended up being used and lack of maintenance meant even the current docker build is not working. Also, the PyPy project's support for Python compatibility doesn't move quickly enough, we might start deprecating Python 3.10 support soon (so we can use Python 3.11 features) but PyPy supports at most Python 3.10 (and support for 3.11 hasn't even started).

Acceptance Criteria

• Remove pypy comment from test matrix (it wasn't enabled, but there was a commented job)
• Remove pypy from docker build (pypy-3.10 was being included, but it has been failing for several releases now)
• Remove pypy from script that generates tags
• Remove pypy from test of the script that generate tags
• Remove pypy dockerfile (Dockerfile.pypy)
• Remove pypy from Makefile (shortcut to build the docker image)

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.96%. Comparing base (71b079a) to head (62ba5a1).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1062   +/-   ##
=======================================
  Coverage   84.95%   84.96%           
=======================================
  Files         300      300           
  Lines       22944    22944           
  Branches     3471     3471           
=======================================
+ Hits        19493    19494    +1     
+ Misses       2767     2764    -3     
- Partials      684      686    +2     

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