Fix tabs in test file to satisfy tidy check

Author: yalagadapavankumar

compiler/rustc_errors/src/markdown/tests/parse.rs

@@ -367,7 +367,7 @@ fn test_snake_case() {
 
 #[test]
 fn test_codeblock_trailing_whitespace() {
-    let buf = "```rust\ncode\n```	\nrest";
+    let buf = "```rust\ncode\n```    \nrest";
     let (t, r) = parse_codeblock(buf.as_bytes());
     assert_eq!(t, MdTree::CodeBlock { txt: "code", lang: Some("rust") });
     assert_eq!(r, b"\nrest");