Add tests for validating yaml (SOFTWARE-3287)

[yzz971115]

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For validating the URL in VO, I use a third party package "validators" - "https://validators.readthedocs.io/en/latest/#". And also, when I try to verify the "verify_resource.py" in my machine, it always raises an UnicodeDecodeError for the yaml.load function, so I can not verify the changes in this file.

[brianhlin]

@yzz971115 I don't believe validators is installed by default so you'll want to update the requirements-apache.txt to add it

[matyasselmeci]

This hasn't been merged in five years so I'm going to close it.