Run HTML linting as part of full lint suite

This command is not used in CI so we can already include the HTML
linting even before the HTML linting is required to pass in CI.

tasks.py

@@ -291,7 +291,7 @@ def test_python(ctx):
 @task
 def lint(ctx):
     """Run linting."""
-    # lint_html(ctx)
+    lint_html(ctx)
     lint_css(ctx)
     lint_js(ctx)
     lint_python(ctx)