fix: resolve remaining fmt and clippy errors

rustfmt (rust 1.95) collapses two multiline match arms in the validation
module onto single lines; apply cargo fmt. Clippy's collapsible_match
also fires on the html5lib tree construction test harness — lift the
inner `if !line.is_empty()` checks into match guards to match the fix
already applied to the library sources in 29f404e.

Author: jonwiggins

src/validation/dtd.rs

@@ -2556,9 +2556,7 @@ fn validate_attributes(
                         column: None,
                     });
                 }
-                (AttributeDefault::Fixed(fixed_val), Some(attr))
-                    if attr.value != *fixed_val =>
-                {
+                (AttributeDefault::Fixed(fixed_val), Some(attr)) if attr.value != *fixed_val => {
                     errors.push(ValidationError {
                         message: format!(
                             "attribute '{}' on element '{elem_name}' must have \

src/validation/xsd.rs

@@ -1775,9 +1775,7 @@ fn validate_builtin_value(
         }
         "dateTime" if !is_valid_datetime_pattern(value) => {
             errors.push(ValidationError {
-                message: format!(
-                    "value \"{value}\" in <{context}> is not a valid dateTime"
-                ),
+                message: format!("value \"{value}\" in <{context}> is not a valid dateTime"),
                 line: None,
                 column: None,
             });

tests/html5lib_tree_construction.rs

@@ -105,15 +105,11 @@ fn parse_test_file(content: &str) -> Vec<TreeTest> {
                     }
                     data.push_str(line);
                 }
-                "errors" => {
-                    if !line.is_empty() {
-                        errors += 1;
-                    }
+                "errors" if !line.is_empty() => {
+                    errors += 1;
                 }
-                "new-errors" => {
-                    if !line.is_empty() {
-                        new_errors += 1;
-                    }
+                "new-errors" if !line.is_empty() => {
+                    new_errors += 1;
                 }
                 "fragment" => {
                     fragment_context = Some(line.to_string());