Bump markdown dependency (#1954)

Bump markdown dependency

Author: srawlins

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## 0.28.3+2
 * Support the latest version of `package:html`.
+* Use latest version of the markdown package.
 
 ## 0.28.3+1
 * Fix scroll physics and behavior for Safari on iOS.

pubspec.yaml

@@ -18,7 +18,7 @@ dependencies:
   http_parser: '>=3.0.3 <4.0.0'
   logging: ^0.11.3+1
   process: ^3.0.5
-  markdown: ^2.0.0
+  markdown: ^2.0.3
   mustache: ^1.1.0
   package_config: '>=0.1.5 <2.0.0'
   path: ^1.3.0