Update `vm_service` constraints to `>=6.0.0 <9.0.0` (#1650)

diff --git a/pkgs/test_core/CHANGELOG.md b/pkgs/test_core/CHANGELOG.md
index f4ce9d5..0a09aac 100644
--- a/pkgs/test_core/CHANGELOG.md
+++ b/pkgs/test_core/CHANGELOG.md
@@ -1,4 +1,5 @@
 ## 0.4.11-dev
+* Update `vm_service` constraint to `>=6.0.0 <9.0.0`.
 
 ## 0.4.10
 
diff --git a/pkgs/test_core/pubspec.yaml b/pkgs/test_core/pubspec.yaml
index a94c4c2..9d5b8a0 100644
--- a/pkgs/test_core/pubspec.yaml
+++ b/pkgs/test_core/pubspec.yaml
@@ -25,7 +25,7 @@
   source_span: ^1.8.0
   stack_trace: ^1.10.0
   stream_channel: ^2.1.0
-  vm_service: ">=6.0.0 <8.0.0"
+  vm_service: ">=6.0.0 <9.0.0"
   yaml: ^3.0.0
   # matcher is tightly constrained by test_api
   matcher: any