django: Fix carrier usage on ASGI requests

For ASGI requests, we must use `request.scope` instead of
`request.META`. This is because `ASGIGetter` retrieves the `headers` key
from the carrier [0], which is only present in `request.scope`.

[0] https://github.com/open-telemetry/opentelemetry-python-contrib/blob/main/instrumentation/opentelemetry-instrumentation-asgi/src/opentelemetry/instrumentation/asgi/__init__.py#L133

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#765](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/765))
 - `opentelemetry-instrumentation-pika` now propagates context to basic_consume callback
   ([#766](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/766))
+- `opentelemetry-instrumentation-django` Fixed carrier usage on ASGI requests.
+  ([#767](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/767))
 
 ## [1.6.2-0.25b2](https://github.com/open-telemetry/opentelemetry-python/releases/tag/v1.6.2-0.25b2) - 2021-10-19
 

instrumentation/opentelemetry-instrumentation-django/src/opentelemetry/instrumentation/django/middleware.py

@@ -184,7 +184,7 @@ def process_request(self, request):
             carrier_getter = wsgi_getter
             collect_request_attributes = wsgi_collect_request_attributes
 
-        token = attach(extract(request_meta, getter=carrier_getter))
+        token = attach(extract(carrier, getter=carrier_getter))
 
         span = self._tracer.start_span(
             self._get_span_name(request),