Use RetryClient from package:http/retry.dart (#2980)

Drop dependency on `http_retry`.

Co-authored-by: Jonas Finnemann Jensen <jonasfj@google.com>
diff --git a/lib/src/http.dart b/lib/src/http.dart
index 054e901..541931f 100644
--- a/lib/src/http.dart
+++ b/lib/src/http.dart
@@ -11,7 +11,7 @@
 import 'dart:math' as math;
 
 import 'package:http/http.dart' as http;
-import 'package:http_retry/http_retry.dart';
+import 'package:http/retry.dart';
 import 'package:pedantic/pedantic.dart';
 import 'package:pool/pool.dart';
 import 'package:stack_trace/stack_trace.dart';
diff --git a/pubspec.yaml b/pubspec.yaml
index 67a8d94..222a5a5 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -14,7 +14,6 @@
   crypto: ^3.0.1
   http: ^0.13.3
   http_multi_server: ^3.0.1
-  http_retry: ^0.2.0
   meta: ^1.3.0
   oauth2: ^2.0.0
   path: ^1.8.0