replace pkg_resources with importlib in ska_helpers.get_version

[javierggt]

Description

This just replaces pkg_resources with importlib.

There are three points where I don't know yet whether changes are needed, but my best guess is what I implemented:

• at the top, a warning is filtered. Is that still needed?

• I removed a check:

  Check if the imported package __init__.py file has the same location
  as the distribution that was found. If working in a local git repo
  that does not have a .egg-info directory, get_distribution()
  will find an installed version

  I believe importlib does find the correct one (I checked on a cheta repo, see below)

• The exceptionat the end used to catch DistributionNotFound and I made it catch metadata.PackageNotFoundError, but I do not know yet whether this will ever happen.

Fixes #55

Interface impacts

None

Testing

Unit tests

• Mac (in 2023.9 with warning)
• Mac (in 2024.0rc7 without warning)

Independent check of unit tests by Jean

• Linux (ska3-flight -- I didn't focus on the warnings and left a pytest.ini in place -- just focused on tests continuing to pass).

jeanconn-fido> ska3
ska3-jeanconn-fido> pytest
====================================================== test session starts =======================================================
platform linux -- Python 3.10.8, pytest-7.2.1, pluggy-1.0.0
rootdir: /proj/sot/ska/jeanproj/git, configfile: pytest.ini
plugins: anyio-3.6.2, timeout-2.1.0
collected 63 items                                                                                                               

ska_helpers/retry/tests/test_retry.py ..........                                                                           [ 15%]
ska_helpers/tests/test_chandra_models.py ..................                                                                [ 44%]
ska_helpers/tests/test_git_helpers.py .                                                                                    [ 46%]
ska_helpers/tests/test_paths.py ......                                                                                     [ 55%]
ska_helpers/tests/test_run_info.py ..                                                                                      [ 58%]
ska_helpers/tests/test_utils.py ..........................                                                                 [100%]

====================================================== 63 passed in 13.65s =======================================================
ska3-jeanconn-fido> git rev-parse HEAD
47518a2dba31afcd68b1b84d87e891a1990f8c56

Functional tests

In [1]: import Ska.arc5gl
   ...: import ska_arc5gl
   ...: import Ska.engarchive
   ...: import cheta
   ...: import ska_helpers  # in local git repo
   ...: 

In [2]: print(f"""
   ...: Ska.arc5gl: {Ska.arc5gl.__version__}
   ...: ska_arc5gl: {ska_arc5gl.__version__}
   ...: Ska.engarchive: {Ska.engarchive.__version__}
   ...: cheta: {cheta.__version__}
   ...: ska_helpers: {ska_helpers.__version__}
   ...: """)

Ska.arc5gl: 4.0.1
ska_arc5gl: 4.0.1
Ska.engarchive: 4.60.0
cheta: 4.60.0
ska_helpers: 0.14.1.dev1+g47518a2

In the cheta repository, made sure to remove all egg directories, changed to the speedy branch, and then:

In [1]: import cheta

In [2]: cheta.__version__
Out[2]: '4.61.1.dev3+g55c4676'

[jeanconn]

This seems fine, though unlike pkg_resources, we're already importing importlib at the top of the file. Does this need to be in this catch_warnings block?

[taldcroft]

Good point. I'm fighting two instincts, (1) cut any code that doesn't seem necessary (and re-test) and (2) let it go and approve and move on. I'm honestly not sure, but otherwise this PR looks good and we should get it merged one way or the other.

[javierggt]

These two sub-modules are not imported by the import statement at the top of the file, so they have to be explicitly imported. This goes to say that the fact that importlib was already imported says nothing about whether the warning would be issued here

I don't know whether importing without the warnings filter would trigger the warning. I do not remember if there were special cases when this was triggered, or if a simple call to testr is enough to check.

[javierggt]

I just removed the filter warning in the master branch, and I did not get this warning, so I do not know in which circumstances this warning was issued to begin with.

[jeanconn]

Seems fine to leave this as is.

[jeanconn]

I'm also wondering what could make sense for a versions unit test, but that's not a lien on this PR.