lint: bump MLC to v0.19.0

Fixes: #31044

This MLC update includes a change which will ignore files being ignored
by git, and help avoid false-positives when linting in this repo.

test/lint/test_runner/src/main.rs

@@ -516,6 +516,7 @@ fn lint_markdown() -> LintResult {
         "--ignore-path",
         md_ignore_path_str.as_str(),
         "--gitignore",
+        "--gituntracked",
         "--root-dir",
         ".",
     ])