What does this PR do?

Dedups the poetry and project sections of the pyproject.toml file.

Motivation

Fixing dependency management of ddtrace version based on Python runtime in the PyPI wheel. Response to #713

Testing Guidelines

CI. Made a sample python package with the new format of the pyproject.toml file and uploaded it to the test PyPI website. Made sure that differentp Python runtimes depend on different versions of ddtrace and that Python 3.10+ users can customize which version of ddtrace 4.X they want to use.

Additional Notes

Types of Changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

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• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
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