fix test

Author: daiyam

tests/lib/snapshots/markdown-test.js.md

@@ -39,7 +39,7 @@ Generated by [AVA](https://ava.li).
 
 > Snapshot 1
 
-    `<pre class="code CodeMirror">␊
+    `<pre class="code CodeMirror" data-line="1">␊
             <span class="filename">filename.js</span>␊
             <span class="lineNumber CodeMirror-gutters"><span class="CodeMirror-linenumber">2</span></span>␊
             <code class="js">var project = 'boostnote';␊