Not really fair to call this a false positive since our annotation is
incorrect, but screw it.

This function is passed an arbitrary JSON value, not a JSONDict.

Before the recent changes, both expressions assigned to D were
coroutines. Now the second expression is a synchronous function
returning a deferred.

```
tests/storage/test_monthly_active_users.py:237: error: Incompatible
types in assignment (expression has type "Deferred[None]", variable has
type "Coroutine[Any, Any, None]")  [assignment]
```

Mypy now includes python/typeshed#6653
which triggered

```
stubs/sortedcontainers/sorteddict.pyi:88: error: Signature of "update" incompatible with supertype "MutableMapping"  [override]
stubs/sortedcontainers/sorteddict.pyi:88: note:      Superclass:
stubs/sortedcontainers/sorteddict.pyi:88: note:          @overload
stubs/sortedcontainers/sorteddict.pyi:88: note:          def update(self, SupportsKeysAndGetItem[_KT, _VT], **kwargs: _VT) -> None
stubs/sortedcontainers/sorteddict.pyi:88: note:          @overload
stubs/sortedcontainers/sorteddict.pyi:88: note:          def update(self, Iterable[Tuple[_KT, _VT]], **kwargs: _VT) -> None
stubs/sortedcontainers/sorteddict.pyi:88: note:          @overload
stubs/sortedcontainers/sorteddict.pyi:88: note:          def update(self, **kwargs: _VT) -> None
stubs/sortedcontainers/sorteddict.pyi:88: note:      Subclass:
stubs/sortedcontainers/sorteddict.pyi:88: note:          @overload
stubs/sortedcontainers/sorteddict.pyi:88: note:          def update(self, Mapping[_KT, _VT], **kwargs: _VT) -> None
stubs/sortedcontainers/sorteddict.pyi:88: note:          @overload
stubs/sortedcontainers/sorteddict.pyi:88: note:          def update(self, Iterable[Tuple[_KT, _VT]], **kwargs: _VT) -> None
stubs/sortedcontainers/sorteddict.pyi:88: note:          @overload
stubs/sortedcontainers/sorteddict.pyi:88: note:          def update(self, **kwargs: _VT) -> None
```

This suppresses the complaint

```
synapse/app/_base.py:491: error: Cannot instantiate abstract class "init" with abstract attribute "__exit__"  [abstract]
```

by including the change in
https://github.com/getsentry/sentry-python/p

I can't see anything obviously terrible in the changelogs; see
https://github.com/getsentry/sentry-python/releases

Additionally, we don't upper bound sentry-sdk, so fresh installations
might be using this version anyway.

grrr at not validating. Y'all need more static typing in your lives.