src/yamerl.app.src: Bump version to 0.10.0

This introduces one new feature: it is now possible to keep duplicate
keys in mappings with the option `{keep_duplicate_keys, boolean()}`
(#52, #53). This flag restores the behavior yamerl had before the 0.9.0
release and the merge of #40.

Thank you to @flurin for his contribution!

src/yamerl.app.src

@@ -5,7 +5,7 @@
     {description,
       "YAML 1.2 and JSON parser in pure Erlang"
     },
-    {vsn, "0.9.0"},
+    {vsn, "0.10.0"},
     {modules, []},
     {registered, [yamerl_sup]},
     {applications, [