Migrate to build 1.0 for sdist

[speth]

Changes proposed in this pull request

• Use updated build API (https://pypa-build.readthedocs.io/en/latest/changelog.html); the old IsolatedEnvBuilder was removed with the 1.0 release.
• Fix a broken link into the pint docs.

If applicable, fill in the issue number this pull request is fixing

This should fix the current error that's breaking the PyPI package builds.

If applicable, provide an example illustrating new features this pull request is introducing

Checklist

• [x] The pull request includes a clear description of this code change
• [x] Commit messages have short titles and reference relevant issues
• [x] Build passes (scons build & scons test) and unit tests address code coverage
• [x] Style & formatting of contributed code follows contributing guidelines
• [x] The pull request is ready for review

[codecov[bot]]

Codecov Report

Merging #1625 (e482b19) into main (baf28af) will decrease coverage by 0.01%. The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #1625      +/-   ##
==========================================
- Coverage   72.71%   72.70%   -0.01%     
==========================================
  Files         370      370              
  Lines       56286    56286              
  Branches    20368    20368              
==========================================
- Hits        40927    40924       -3     
- Misses      12363    12365       +2     
- Partials     2996     2997       +1     

see 1 file with indirect coverage changes

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[bryanwweber]

Merged, thanks @speth