Fix bool coercion to 0/1

[jtcohen6]

resolves #4511

This is a better fix because it:

• Targets the exact change we want to undo (this one: Allow the conversion of booleans to numbers wireservice/agate#733)
• Enables us to upgrade to newer versions of agate if they offer security fixes, etc.

-- models/any_model.sql
{% if execute %}

  {% set results = run_query('''
    select true as my_boolean_column, 0 as my_numeric_column
    union all
    select false, 1
  ''') %}

  {{ results.print_table() }}

{% endif %}

Before:

| my_boolean_column | my_numeric_column |
| ----------------- | ----------------- |
|                 1 |                 0 |
|                 0 |                 1 |

After:

| my_boolean_column | my_numeric_column |
| ----------------- | ----------------- |
|              True |                 0 |
|             False |                 1 |