prep for stable release (#354)

prep for stable release
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 98f6da6..16b95ac 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+## 4.0.0-dev
+
+* Update `args` dep to allow the latest stable, update all `-nullsafety`
+  pre-release deps to depend on stable versions.
+
 ## 4.0.0-nullsafety.0
 
 * Migrate package to Dart's null safety language feature, requiring Dart
diff --git a/lib/src/version.dart b/lib/src/version.dart
index 30fedeb..e460372 100644
--- a/lib/src/version.dart
+++ b/lib/src/version.dart
@@ -1,2 +1,2 @@
 // Generated code. Do not modify.
-const packageVersion = '4.0.0-nullsafety.0';
+const packageVersion = '4.0.0-dev';
diff --git a/pubspec.yaml b/pubspec.yaml
index 1c66d23..e93f86a 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: markdown
-version: 4.0.0-nullsafety.0
+version: 4.0.0-dev
 
 description: A portable Markdown library written in Dart that can parse
  Markdown into HTML.
@@ -12,19 +12,19 @@
   sdk: '>=2.12.0-0 <3.0.0'
 
 dependencies:
-  args: ^1.0.0
-  charcode: ^1.2.0-nullsafety.3
-  meta: ^1.3.0-nullsafety.6
+  args: '>=1.0.0 <3.0.0'
+  charcode: ^1.2.0
+  meta: ^1.3.0
 
 dev_dependencies:
   build_runner: ^1.0.0
   build_version: ^2.0.0
   build_web_compilers: '>=1.0.0 <3.0.0'
-  collection: ^1.15.0-nullsafety.5
+  collection: ^1.15.0
   html: '>=0.12.2 <0.15.0'
   io: ^0.3.2+1
-  js: ^0.6.3-nullsafety.3
-  path: ^1.8.0-nullsafety.3
-  pedantic: ^1.10.0-nullsafety.3
-  test: ^1.16.0-nullsafety.13
-  yaml: ^3.0.0-nullsafety.0
+  js: ^0.6.3
+  path: ^1.8.0
+  pedantic: ^1.10.0
+  test: ^1.16.0
+  yaml: ^3.0.0