Add gourmet traveller

[mlduff]

Adds support for Gourmet Traveller, using https://www.gourmettraveller.com.au/recipe/mains/greek-grilled-calamari-salad/ as the test case recipe. I made a few notes in the issue for review consideration.

Resolves https://github.com/hhursev/recipe-scrapers/issues/1103

[jknndy]

@mlduff, there doesn't appear to be ratings data available on this site so you can omit it in the scraper class (check out #1025 & #1065 for some related convo) & we'll need test coverage for category & cuisine

[mlduff]

@jayaddison I've implemented changes that only remove one instance of each group heading, so if there are group headings which are also ingredients then they won't both be removed.

[jayaddison]

Thanks @mlduff!