[css-ui-3] Fix typo in implementation report

Author: frivoal

css-ui-3/implementation-report.html

@@ -166,7 +166,7 @@ <h2 id=tests><a href="#tests" class=self-link></a>Tests</h2>
 
 <p class=note>Note that the link above also includes tests from other test suites that reference this specification.
 At the time of writing this report, this includes one test (<a href="https://test.csswg.org/harness/test/css-ui-3_dev/single/grid-box-sizing-001/">grid-box-sizing-001</a>) that is part of the <a href="https://drafts.csswg.org/css-grid/">css-grid</a> test suite.
-As that specification is less this one on TR,
+As that specification is less advanced than this one on TR,
 this report does not take this test into account.
 
 <p>The test suite contains 203 tests for mandatory normative statements