Drop support for awkward v1

[Saransh-cpp]

Description

Kindly take a look at CONTRIBUTING.md.

Please describe the purpose of this pull request. Reference and link to any relevant issues or pull requests.

Checklist

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't any other open Pull Requests for the required change?
• Does your submission pass pre-commit? ($ pre-commit run --all-files or $ nox -s lint)
• Does your submission pass tests? ($ pytest or $ nox -s tests)
• Does the documentation build with your changes? ($ cd docs; make clean; make html or $ nox -s docs)
• Does your submission pass the doctests? ($ pytest --doctest-plus src/vector/ or $ nox -s doctests)

Before Merging

• Summarize the commit messages into a brief review of the Pull request.

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 82.79%. Comparing base (23f1c42) to head (af9000a).

Files	Patch %	Lines
src/vector/__init__.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #434      +/-   ##
==========================================
+ Coverage   82.77%   82.79%   +0.02%     
==========================================
  Files          96       96              
  Lines       11583    11575       -8     
==========================================
- Hits         9588     9584       -4     
+ Misses       1995     1991       -4     

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[jpivarski]

This is great, but you want to be careful about when you merge it. When you merge it in and publish a release 1.4.0, there will be a dividing line: users of Awkward 1 (such as users of Coffea 0.7) will be more restricted in which Vector version they can take. Ideally, this should happen in a relatively quiet time when there aren't other important changes going in, so that someone isn't forced to switch Awkward versions because they need a small Vector feature that went in after 1.4.0. In cases like that, they'd probably ask for the new Vector feature to be back-ported to 1.3.x. Doing this during a busy time would mean adding the extra work of back-porting to that work.

Is it a relatively quiet time now? The Coffea-Vector synchronization that's going on now, is that strictly Coffea 2024 (not 0.7), which is already Awkward 2 so the above wouldn't be an issue?

Also, immediately before merging this PR, make a branch off of main called main-1.3, which will make it easier to back-port. Back-port PRs would merge into main-1.3, rather than main.

[Saransh-cpp]

Thanks for the review! That makes sense, I'll create a new branch before merging the PR. I think I'll hold this till coffea migrates to vector as the process has already changed several things in vector.

[Saransh-cpp]

Now that coffea has switched to vector and the changes are up in a release, it should be okay to merge this in. I will wait for a couple of weeks before merging this, just in case we get some suggestions from coffee users. I think pyhep.dev would be the perfect place to merge this in and create a new release.