Bump version to 0.12.12-dev (#182)

* Dependency override for version bump

Co-authored-by: Nate Bosch <nbosch@google.com>

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index cc527d1..9b1d426 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,5 @@
+## 0.12.12-dev
+
 ## 0.12.11
 
 * Change many argument types from `dynamic` to `Object?`.

pubspec.yaml

diff --git a/pubspec.yaml b/pubspec.yaml
index f092d9f..5ea68ae 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: matcher
-version: 0.12.11
+version: 0.12.12-dev
 
 description: >-
   Support for specifying test expectations via an extensible Matcher class.
@@ -17,3 +17,6 @@
   test: any
   test_api: any
   test_core: any
+
+dependency_overrides:
+  test_api: any