remove redundant experiment (dart-lang/string_scanner#31)

* remove redundant experiment

* bump dev version

* bump dev version
diff --git a/pkgs/string_scanner/CHANGELOG.md b/pkgs/string_scanner/CHANGELOG.md
index c8c7008..08216dc 100644
--- a/pkgs/string_scanner/CHANGELOG.md
+++ b/pkgs/string_scanner/CHANGELOG.md
@@ -1,3 +1,5 @@
+## 1.1.0-nullsafety.4-dev
+
 ## 1.1.0-nullsafety.3
 
 * Update SDK constraints to `>=2.12.0-0 <3.0.0` based on beta release
diff --git a/pkgs/string_scanner/analysis_options.yaml b/pkgs/string_scanner/analysis_options.yaml
index 2407da6..60abe63 100644
--- a/pkgs/string_scanner/analysis_options.yaml
+++ b/pkgs/string_scanner/analysis_options.yaml
@@ -4,9 +4,6 @@
   strong-mode:
     implicit-casts: false
 
-  enable-experiment:
-  - non-nullable
-
 linter:
   rules:
     - avoid_bool_literals_in_conditional_expressions
diff --git a/pkgs/string_scanner/pubspec.yaml b/pkgs/string_scanner/pubspec.yaml
index 6099c54..0d29f2e 100644
--- a/pkgs/string_scanner/pubspec.yaml
+++ b/pkgs/string_scanner/pubspec.yaml
@@ -1,5 +1,5 @@
 name: string_scanner
-version: 1.1.0-nullsafety.3
+version: 1.1.0-nullsafety.4-dev
 
 description: A class for parsing strings using a sequence of patterns.
 homepage: https://github.com/dart-lang/string_scanner