Add *.ron syntax mapping

Add a mapping to use `Rust` for rusty object notation, identified by `.ron` extension. See [#2427](https://github.com/sharkdp/bat/issues/2427).

src/syntax_mapping.rs

@@ -156,6 +156,10 @@ impl<'a> SyntaxMapping<'a> {
             .insert("*.hook", MappingTarget::MapTo("INI"))
             .unwrap();
 
+        mapping
+            .insert("*.ron", MappingTarget::MapTo("Rust"))
+            .unwrap();
+
         // Global git config files rooted in `$XDG_CONFIG_HOME/git/` or `$HOME/.config/git/`
         // See e.g. https://git-scm.com/docs/git-config#FILES
         if let Some(xdg_config_home) =