Update front page test count

Current exact count is 53814.

Author: zayenz

index.html

@@ -57,5 +57,5 @@ <h2>Gecode</h2>
       efficient base system an additional edge.</dd>
   </dl>
   <dt>tested</dt>
-  <dd>Gecode uses a test suite with almost 50000 different test cases reaching a test coverage close to 100%.</dd>
+  <dd>Gecode uses a test suite with more than 50000 different test cases reaching a test coverage close to 100%.</dd>
   </dl>