Fix Faker::Dog and add tests

[wtanna]

This PR Does the following:

• Faker::Dog was actually Faker::Cat. Updated to the correct class name
• Added more random data to Faker::Dog
• Added tests for Faker::Dog
• Updated the Regex in Faker::University to check for Greek Letters. CI kept failing because when it was generating the 3 letter greek_organization they were all Greek Letters and not word characters \w. There is a chance that one character could be a word character, allowing the tests to pass. I was just very unlucky it seems.