Commercetools

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- Implement testing shipping method actions

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- Add Api clients service
- Testing server now autoreloads on python changes (using Werkzeug)
- Regenerate types from commercetools-api-reference (fixes typos, some new fields, adds extension response errors)
- Add X-Correlation-ID to exception class
- Mock X-Correlation-ID header in testing framework

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- Implement testing predicates gte and lte
- Implement inventory testing actions

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- Implement testing actions 'changeLabel' and 'changeLocalizedEnumValueLabel' for product type

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- Generate the code normally created by the attrs package to improve the
import time with 30%. Attrs is now also no longer a dependency
- Add py.typed placeholder file (PEP561)
- Add support for the ShoppingList service endpoint (including mock interface)
- Add support for the Reviews endpoint (including mock interface)

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- Tax rates ids are now correctly generated