0.15.0

• Breaking change: The ASGI middleware will now raise an exception if contextvars are not available, like it is already the case for other asyncio integrations.
• Contextvars are now used in more circumstances following a bugfix release of gevent. This will fix a few instances of wrong request data being attached to events while using an asyncio-based web framework.
• APM: Fix a bug in the SQLAlchemy integration where a span was left open if the database transaction had to be rolled back. This could have led to deeply nested span trees under that db query span.
• Fix a bug in the Pyramid integration where the transaction name could not be overridden at all.
• Fix a broken type annotation on capture_exception.
• Basic support for Django 3.1. More work is required for async middlewares to be instrumented properly for APM.