Release build_web_compilers 4.1.2. (#3895)

Author: davidmorgan

build_web_compilers/CHANGELOG.md

@@ -1,4 +1,4 @@
-## 4.1.2-wip
+## 4.1.2
 
 - Bump the min SDK to 3.7.0.
 - Use `build_test` 3.0.0.

build_web_compilers/pubspec.yaml

@@ -1,5 +1,5 @@
 name: build_web_compilers
-version: 4.1.2-wip
+version: 4.1.2
 description: Builder implementations wrapping the dart2js and DDC compilers.
 repository: https://github.com/dart-lang/build/tree/master/build_web_compilers
 resolution: workspace