update build_web_compilers dep (#42)

diff --git a/pubspec.yaml b/pubspec.yaml
index 89b63a0..56364a1 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -9,7 +9,7 @@
 
 dev_dependencies:
   build_runner: ^1.1.0
-  build_web_compilers: ^1.0.0
+  build_web_compilers: '>=1.0.0 <3.0.0'
   mockito: ^4.0.0
   path: ^1.1.0
   pedantic: ^1.4.0