**Apache Airflow version**: 1.10.12

**Environment**:  Centos 7 Host

- **Cloud provider or hardware configuration**: 
- **OS** (e.g. from /etc/os-release): Ubuntu 20.04 Docker Container
- **Kernel** (e.g. `uname -a`): Linux c6c6e8230c17 3.10.0-1127.18.2.el7.x86_64 #1 SMP Sun Jul 26 15:27:06 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
- **Install tools**: Docker Compose
- **Others** ?

**What happened**:

The schema file generated by MSSQLToGCSOperator specifies that a field defined as **bit** in MSSQL, is defined as **INTEGER**.  However, the JSON file defines the value as **true**/**false**.  When attempting to import into BigQuery using the GCSOperatorToBigQuery operator, the job fails:
`Error while reading data, error message: JSON parsing error in row starting at position 0: Could not convert value 'boolean_value: false' to integer. Field: manager; Value: 0`

**What you expected to happen**:

Value should be defined as **BOOLEAN** in the schema.

**How to reproduce it**:
Ensure `dbo.Customers` table has a **bit** column:

```
export_customers = MsSqlToGoogleCloudStorageOperator(
                task_id='export_customers',
                sql='SELECT * FROM dbo.Customers;',
                bucket='mssql-export',
                filename='data/customers/export.json',
                schema_filename='schemas/export.json',
                mssql_conn_id='mssql_default',
                google_cloud_storage_conn_id='google_cloud_default',
                dag=dag
            )
```
#
#
#
from __future__ import annotations
import datetime
from unittest import mock
import pytest
try:
    from airflow.providers.google.cloud.transfers.mssql_to_gcs import MSSQLToGCSOperator
except ImportError:
    pytest.skip("MSSQL not available", allow_module_level=True)
TASK_ID = "test-mssql-to-gcs"
MSSQL_CONN_ID = "mssql_conn_test"
SQL = "select 1"
BUCKET = "gs://test"
JSON_FILENAME = "test_{}.ndjson"
GZIP = False
ROWS = [("mock_row_content_1", 42), ("mock_row_content_2", 43), ("mock_row_content_3", 44)]