Unit tests for scripts/parse_and_validate_properties_txt.py

[mingness]

This script has pydantic objects with validation - these could be tests for expected behavior.
There are also seven functions -

• read_properties_txt makes a request, so this will need to be mocked, and edge cases tests
• all other functions except for set_output and set_output_error can be tested with mock data.
• set_output and set_output_error don't need to be tested, as these are specific to the github actions

[mingness]

with #95 , added tests to pydantic objects
with #101, test validate_existing, validate_new, validate_new_library

remaining work would be to write tests for parse_text and read_properties_txt