Prepare for 1.6.4 release

Includes upgrade to vm_service 12.0.0

Author: bkonyi

CHANGELOG.md

@@ -1,8 +1,9 @@
-## 1.6.4-wip.
+## 1.6.4
 
 - allow omitting space between `//` and `coverage` in coverage ignore comments
 - allow text after coverage ignore comments
 - throw FormatException when encountering unbalanced ignore comments instead of silently erroring
+- Update `package:vm_service` constraints to '>= 9.4.0 <12.0.0'.
 
 ## 1.6.3
 

pubspec.yaml

@@ -1,10 +1,10 @@
 name: coverage
-version: 1.6.3
+version: 1.6.4
 description: Coverage data manipulation and formatting
 repository: https://github.com/dart-lang/coverage
 
 environment:
-  sdk: '>=2.18.0 <3.0.0'
+  sdk: '>=2.18.0 <4.0.0'
 
 dependencies:
   args: ^2.0.0
@@ -13,7 +13,7 @@ dependencies:
   path: ^1.8.0
   source_maps: ^0.10.10
   stack_trace: ^1.10.0
-  vm_service: '>=9.4.0 <12.0.0'
+  vm_service: '>=9.4.0 <13.0.0'
 
 dev_dependencies:
   benchmark_harness: ^2.2.0