Re-cookiecut, move tests to root level

[bobleesj]

Closes #209, #207, #175, #162, #37

[bobleesj]

Looking into the CI tests.

[bobleesj]

Seems like there is a typo of xport instead of export in https://github.com/Billingegroup/release-scripts/blob/main/.github/workflows/_tests-on-pr.yml

      - name: Validate ${{ inputs.project }}
        run: |
          if ${{ inputs.headless }}; then
            xport DISPLAY=:99

Created a PR: scikit-package/release-scripts#45

Once the PR is merged, hopefully the CI passes.

[bobleesj]

Removed pinning since the latest release on conda-forge (diffpy.structure, diffpy.pdffit2 have no numpy pinning)

[bobleesj]

In proproject.toml, however, still maintained below as discussed regarding the wx problem.

        'Programming Language :: Python :: 3.10',
        'Programming Language :: Python :: 3.11',

[bobleesj]

@sbillinge Just noticed that xport to export typo must be also fixed in v0 of the release script as well as main. Created a PR: scikit-package/release-scripts#46

[sbillinge]

I reran the tests after merging main into v0 and the tests failed in the same way. @bobleesj Pls could you take a quick look. I think it is probably something very simple.

[bobleesj]

(Still running tests using my own local fork) I will ping @sbillinge once ready for review.

[bobleesj]

I think it's ready @sbillinge Had to pin numpy < 2 but made an issue

#212