use latest deps, drop dep overrides (dart-lang/timing#18)

diff --git a/pkgs/timing/lib/src/timing.g.dart b/pkgs/timing/lib/src/timing.g.dart
index 64b64ef..679c082 100644
--- a/pkgs/timing/lib/src/timing.g.dart
+++ b/pkgs/timing/lib/src/timing.g.dart
@@ -6,25 +6,22 @@
 // JsonSerializableGenerator
 // **************************************************************************
 
-TimeSlice _$TimeSliceFromJson(Map<String, dynamic> json) {
-  return TimeSlice(
-    DateTime.parse(json['startTime'] as String),
-    DateTime.parse(json['stopTime'] as String),
-  );
-}
+TimeSlice _$TimeSliceFromJson(Map<String, dynamic> json) => TimeSlice(
+      DateTime.parse(json['startTime'] as String),
+      DateTime.parse(json['stopTime'] as String),
+    );
 
 Map<String, dynamic> _$TimeSliceToJson(TimeSlice instance) => <String, dynamic>{
       'startTime': instance.startTime.toIso8601String(),
       'stopTime': instance.stopTime.toIso8601String(),
     };
 
-TimeSliceGroup _$TimeSliceGroupFromJson(Map<String, dynamic> json) {
-  return TimeSliceGroup(
-    (json['slices'] as List<dynamic>)
-        .map((e) => TimeSlice.fromJson(e as Map<String, dynamic>))
-        .toList(),
-  );
-}
+TimeSliceGroup _$TimeSliceGroupFromJson(Map<String, dynamic> json) =>
+    TimeSliceGroup(
+      (json['slices'] as List<dynamic>)
+          .map((e) => TimeSlice.fromJson(e as Map<String, dynamic>))
+          .toList(),
+    );
 
 Map<String, dynamic> _$TimeSliceGroupToJson(TimeSliceGroup instance) =>
     <String, dynamic>{
diff --git a/pkgs/timing/pubspec.yaml b/pkgs/timing/pubspec.yaml
index 08e2442..16588b9 100644
--- a/pkgs/timing/pubspec.yaml
+++ b/pkgs/timing/pubspec.yaml
@@ -12,12 +12,7 @@
   json_annotation: ^4.0.0
 
 dev_dependencies:
-  build_runner: ^1.0.0
-  json_serializable: ^4.0.0
+  build_runner: ^2.0.0
+  json_serializable: ^5.0.0
   pedantic: ^1.1.0
   test: ^1.0.0
-
-dependency_overrides:
-  # Remove these when they are updated to support the latest pkg:timing
-  build_runner: ^1.0.0
-  build_runner_core: ^6.0.0