feat: Use ddtrace 1.6.3

[astuyve]

What does this PR do?

Updates dd-trace-py to 1.6.3

Motivation

Closes #271

Testing Guidelines

Additional Notes

Types of Changes

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

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• This PR contains breaking changes that are documented in the description
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