Remove dependency on package:retry (#4617)

Author: sigurdm

pubspec.lock

@@ -257,14 +257,6 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.2.0"
-  retry:
-    dependency: "direct main"
-    description:
-      name: retry
-      sha256: "822e118d5b3aafed083109c72d5f484c6dc66707885e07c0fbcb8b986bba7efc"
-      url: "https://pub.dev"
-    source: hosted
-    version: "3.1.2"
   shelf:
     dependency: "direct main"
     description:

pubspec.yaml

@@ -20,7 +20,6 @@ dependencies:
   path: ^1.9.1
   pool: ^1.5.1
   pub_semver: ^2.2.0
-  retry: ^3.1.2
   shelf: ^1.4.2
   source_span: ^1.10.1
   stack_trace: ^1.12.1