Changes proposed in this pull request
This will direct pip to build in place and not in a temporary directory. Future versions of pip will not be building in a temporary directory according to a depreciation warning:

DEPRECATION: A future pip version will change local packages to be built in-place without first copying to a temporary directory. We recommend you use --use-feature=in-tree-build to test your packages with this new behavior before it becomes the default. pip 21.3 will remove support for this functionality. You can find discussion regarding this at https://github.com/pypa/pip/issues/7555.

• Add the --use-feature=in-tree-build to pip in the SConscript file for the python build

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Closes #1260

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Checklist

• 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
• Style & formatting of contributed code follows contributing guidelines
• The pull request is ready for review