fix: set the default value of DocumentStatus.updated_at to None. (#68)

<!-- begin-generated-description -->

This pull request updates the `DocumentStatus` class in the
`datasources.py` file and the `version` in the `pyproject.toml` file.

## Changes
- The `updated_at` field in the `DocumentStatus` class is now set to
`None` by default.
- The `version` in the `pyproject.toml` file is updated from `0.10.0` to
`0.10.1`.

<!-- end-generated-description -->

cohere/compass/models/datasources.py

@@ -55,4 +55,4 @@ class DocumentStatus(pydantic.BaseModel):
     state: str
     destinations: typing.List[str]
     created_at: datetime.datetime
-    updated_at: typing.Optional[datetime.datetime]
+    updated_at: typing.Optional[datetime.datetime] = None

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "compass-sdk"
-version = "0.10.0"
+version = "0.10.1"
 authors = []
 description = "Compass SDK"
 readme = "README.md"