Simplify match

This takes advantage of the default match bindings in Rust 2018.

src/markdown_deps.rs

@@ -63,7 +63,7 @@ fn find_toml_blocks(text: &str) -> Vec<CodeBlock<'_>> {
     let mut code_blocks = Vec::new();
     for (event, range) in parser.into_offset_iter() {
         match event {
-            Event::Start(Tag::CodeBlock(Fenced(ref lang))) if is_toml_block(lang) => {
+            Event::Start(Tag::CodeBlock(Fenced(lang))) if is_toml_block(&lang) => {
                 let line_count = text[..range.start].lines().count();
                 let code_block = &text[range];
                 let start = 1 + code_block.find('\n').unwrap_or(0);