Accounting for nodes that are .sql test files

[pgoslatara]

Resolves #

Problem

Solution

Checklist

• [ ] I have run this code in development, and it appears to resolve the stated issue.
• [ ] This PR includes tests, or tests are not required or relevant for this PR.

[github-actions[bot]]

Coverage Report

File	Stmts	Miss	Cover	Missing
src/dbt_bouncer
config_file_validator.py	63	2	97%	161, 167
parsers.py	139	2	99%	193, 441
runner.py	75	4	95%	134, 167–168, 229
utils.py	81	4	95%	30, 35, 125, 149
src/dbt_bouncer/checks/manifest
check_models.py	199	1	99%	593
check_unit_tests.py	24	2	92%	69, 121
src/dbt_bouncer/checks/run_results
check_run_results.py	22	2	91%	56–57
TOTAL	979	17	98%

Tests	Skipped	Failures	Errors	Time
218	0 :zzz:	0 :x:	0 :fire:	40.465s :stopwatch: