revert updating the type for YamlScalar.value (dart-lang/yaml#139)

pkgs/yaml/lib/src/equality.dart

diff --git a/pkgs/yaml/lib/src/equality.dart b/pkgs/yaml/lib/src/equality.dart
index 77cf8e0..5492c49 100644
--- a/pkgs/yaml/lib/src/equality.dart
+++ b/pkgs/yaml/lib/src/equality.dart
@@ -103,7 +103,7 @@
 int deepHashCode(Object? obj) {
   var parents = [];
 
-  int deepHashCodeInner(value) {
+  int deepHashCodeInner(Object? value) {
     if (parents.any((parent) => identical(parent, value))) return -1;
 
     parents.add(value);
@@ -115,7 +115,7 @@
       } else if (value is Iterable) {
         return const IterableEquality().hash(value.map(deepHashCode));
       } else if (value is YamlScalar) {
-        return value.value.hashCode;
+        return (value.value as Object?).hashCode;
       } else {
         return value.hashCode;
       }

pkgs/yaml/lib/src/yaml_node.dart

diff --git a/pkgs/yaml/lib/src/yaml_node.dart b/pkgs/yaml/lib/src/yaml_node.dart
index fb10de3..c8f1e23 100644
--- a/pkgs/yaml/lib/src/yaml_node.dart
+++ b/pkgs/yaml/lib/src/yaml_node.dart
@@ -152,7 +152,7 @@
 /// A wrapped scalar value parsed from YAML.
 class YamlScalar extends YamlNode {
   @override
-  final Object? value;
+  final dynamic value;
 
   /// The style used for the scalar in the original document.
   final ScalarStyle style;