fix: types for logging integration args (getsentry#444)

* fix: types for logging integration args

The sdk supports disabling the LoggingIntegration by passing `None` as
arguments; however, the current types require ints.

This behavior is noted in the docs:
https://docs.sentry.io/platforms/python/logging/#options

```
sentry_sdk.init(integrations=[LoggingIntegration(level=None, event_level=None)])
```

* fix: type for integration's arg

```python
integrations = [
    LoggingIntegration(level=None, event_level=None)  # type: ignore
]
sentry_sdk.init(integrations=integrations)
```

here are the type errors from mypy

```
Argument "integrations" to "init" has incompatible type "List[LoggingIntegration]"; expected "List[Integration]"
"List" is invariant -- see http://mypy.readthedocs.io/en/latest/common_issues.html#variance
Consider using "Sequence" instead, which is covariant
```

* add missing import

Author: sbdchd

sentry_sdk/consts.py

@@ -8,6 +8,7 @@
     from typing import Type
     from typing import Dict
     from typing import Any
+    from typing import Sequence
 
     from sentry_sdk.transport import Transport
     from sentry_sdk.integrations import Integration
@@ -27,7 +28,7 @@ def __init__(
         environment=None,  # type: Optional[str]
         server_name=None,  # type: Optional[str]
         shutdown_timeout=2,  # type: int
-        integrations=[],  # type: List[Integration]
+        integrations=[],  # type: Sequence[Integration]
         in_app_include=[],  # type: List[str]
         in_app_exclude=[],  # type: List[str]
         default_integrations=True,  # type: bool

sentry_sdk/integrations/logging.py

@@ -19,6 +19,7 @@
     from logging import LogRecord
     from typing import Any
     from typing import Dict
+    from typing import Optional
 
 DEFAULT_LEVEL = logging.INFO
 DEFAULT_EVENT_LEVEL = logging.ERROR
@@ -40,7 +41,7 @@ class LoggingIntegration(Integration):
     identifier = "logging"
 
     def __init__(self, level=DEFAULT_LEVEL, event_level=DEFAULT_EVENT_LEVEL):
-        # type: (int, int) -> None
+        # type: (Optional[int], Optional[int]) -> None
         self._handler = None
         self._breadcrumb_handler = None