Fix line numbers not matching up to code in code viewer.

app/assets/stylesheets/framework/highlight.scss

@@ -47,7 +47,7 @@
       font-family: $monospace_font;
       display: block;
       font-size: $code_font_size !important;
-      line-height: 19px;
+      min-height: 19px;
       white-space: nowrap;
 
       i {

changelogs/unreleased/29811-fix-line-number-alignment.yml

+---
+title: Fix the alignment of line numbers to lines of code in code viewer 
+merge_request: 13403
+author: Trevor Flynn
\ No newline at end of file