Fix JSON-LD tests
Fix JSON-LD tests

There is no reason to test for `site` variables each time we check
JSON-LD. Let's only test what we say we are going to test at each stage.

benbalter/jekyll-seo-tag,benbalter/jekyll-seo-tag,jekyll/jekyll-seo-tag,benbalter/jekyll-seo-tag,jekyll/jekyll-seo-tag,jekyll/jekyll-seo-tag