Disable the entity test because the failure case needs LaTeX fragments implemented first to work.

build.rs

@@ -79,6 +79,7 @@ fn is_expect_fail(name: &str) -> Option<&str> {
         "element_container_priority_greater_block_greater_block" => Some("Need to implement subscript."),
         "element_container_priority_section_greater_block" => Some("Need to implement subscript."),
         "paragraphs_paragraph_with_backslash_line_breaks" => Some("The text we're getting out of the parse tree is already processed to remove line breaks, so our comparison needs to take that into account."),
+        "entity_simple" => Some("Need to implement LaTeX fragments."),
         _ => None,
     }
 }