allow the 2.12 prerelease sdks (#1357)

diff --git a/pkgs/test/CHANGELOG.md b/pkgs/test/CHANGELOG.md
index 08edf8c..29357ae 100644
--- a/pkgs/test/CHANGELOG.md
+++ b/pkgs/test/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 1.16.0-nullsafety.7
+
+* Allow prerelease versions of the 2.12 sdk.
+
 ## 1.16.0-nullsafety.6
 
 * Add `markTestSkipped` API.
diff --git a/pkgs/test/pubspec.yaml b/pkgs/test/pubspec.yaml
index ac3160c..4b68424 100644
--- a/pkgs/test/pubspec.yaml
+++ b/pkgs/test/pubspec.yaml
@@ -1,11 +1,11 @@
 name: test
-version: 1.16.0-nullsafety.6
+version: 1.16.0-nullsafety.7
 description: A full featured library for writing and running Dart tests.
 homepage: https://github.com/dart-lang/test/blob/master/pkgs/test
 
 environment:
   # This must remain a tight constraint until nnbd is stable
-  sdk: '>=2.10.0-0 <2.11.0'
+  sdk: '>=2.10.0-0 <2.12.0'
 
 dependencies:
   analyzer: '>=0.36.0 <0.41.0'
@@ -32,8 +32,8 @@
   webkit_inspection_protocol: ">=0.5.0 <0.8.0"
   yaml: ^2.0.0
   # Use an exact version until the test_api and test_core package are stable.
-  test_api: 0.2.19-nullsafety.3
-  test_core: 0.3.12-nullsafety.6
+  test_api: 0.2.19-nullsafety.4
+  test_core: 0.3.12-nullsafety.7
 
 dev_dependencies:
   fake_async: ^1.0.0
diff --git a/pkgs/test_api/CHANGELOG.md b/pkgs/test_api/CHANGELOG.md
index 11159cd..48a4ba5 100644
--- a/pkgs/test_api/CHANGELOG.md
+++ b/pkgs/test_api/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.2.19-nullsafety.4
+
+* Allow prerelease versions of the 2.12 sdk.
+
 ## 0.2.19-nullsafety.3
 
 * Add capability to filter to a single exact test name in `Declarer`.
diff --git a/pkgs/test_api/pubspec.yaml b/pkgs/test_api/pubspec.yaml
index dc3c7ab..2c8d7f1 100644
--- a/pkgs/test_api/pubspec.yaml
+++ b/pkgs/test_api/pubspec.yaml
@@ -1,11 +1,11 @@
 name: test_api
-version: 0.2.19-nullsafety.3
+version: 0.2.19-nullsafety.4
 description: A library for writing Dart tests.
 homepage: https://github.com/dart-lang/test/blob/master/pkgs/test_api
 
 environment:
   # This must remain a tight constraint until nnbd is stable
-  sdk: '>=2.10.0-0 <2.11.0'
+  sdk: '>=2.10.0-0 <2.12.0'
 
 dependencies:
   async: '>=2.5.0-nullsafety <2.5.0'
diff --git a/pkgs/test_core/CHANGELOG.md b/pkgs/test_core/CHANGELOG.md
index 070b0e5..365bf84 100644
--- a/pkgs/test_core/CHANGELOG.md
+++ b/pkgs/test_core/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.3.12-nullsafety.7
+
+* Allow prerelease versions of the 2.12 sdk.
+
 ## 0.3.12-nullsafety.6
 
 * Add experimental `directRunTests`, `directRunSingle`, and `enumerateTestCases`
diff --git a/pkgs/test_core/pubspec.yaml b/pkgs/test_core/pubspec.yaml
index bc9cc5f..261eedf 100644
--- a/pkgs/test_core/pubspec.yaml
+++ b/pkgs/test_core/pubspec.yaml
@@ -1,11 +1,11 @@
 name: test_core
-version: 0.3.12-nullsafety.6
+version: 0.3.12-nullsafety.7
 description: A basic library for writing tests and running them on the VM.
 homepage: https://github.com/dart-lang/test/blob/master/pkgs/test_core
 
 environment:
   # This must remain a tight constraint until nnbd is stable
-  sdk: '>=2.10.0-59.0.dev <2.11.0'
+  sdk: '>=2.10.0-59.0.dev <2.12.0'
 
 dependencies:
   analyzer: ">=0.39.5 <0.41.0"
@@ -31,7 +31,7 @@
   # matcher is tightly constrained by test_api
   matcher: any
   # Use an exact version until the test_api package is stable.
-  test_api: 0.2.19-nullsafety.3
+  test_api: 0.2.19-nullsafety.4
 
 dependency_overrides:
   test_api: