Convert oid expiration timestamp to datetime.datetime (#801)

Co-authored-by: DWSR <brandonmcnama@outlook.com>
Co-authored-by: harrisonfritz <myjunkdrawer@gmail.com>

dask_kubernetes/common/auth.py

@@ -162,7 +162,9 @@ async def refresh_oid_token(self):
             self.token_expire_ts <= datetime.datetime.now(tz=tzUTC)
         ):
             await self._refresh_oidc(provider)
-            expires = self.extract_oid_expiration_from_provider(provider=provider)
+            expires = datetime.datetime.fromtimestamp(
+                self.extract_oid_expiration_from_provider(provider=provider)
+            )
 
             await self.create_refresh_task_from_expiration_timestamp(
                 expiration_timestamp=expires