Fixes issue #8014, _check_type flag not being honored.

[fbl100]

Updated model_utils.mustache to pass the check_type flag into attempt_convert_item(). Failure to do so
results in type validation errors occurring when the user has specifically requested that they be disabled.

@spacether if this is not the 'right' way to fix this, then I may need some assistance with my model. This fix works for my code.

Fixes:
#8014

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[fbl100]

Regarding the failure in the CircleCI build... I don't understand why this is failing. The test in question appears to be using a java client, and this PR does not touch the java client.

[spacether]

Thank you for the PR! This looks great!

[spacether]

looks good to me