Bump version to 1.2.0 (#132)

And fix `char` on arm64 linux, it should be unsigned.
diff --git a/.github/workflows/test-package.yml b/.github/workflows/test-package.yml
index ba8336d..a96f82e 100644
--- a/.github/workflows/test-package.yml
+++ b/.github/workflows/test-package.yml
@@ -47,7 +47,7 @@
       matrix:
         # Add macos-latest and/or windows-latest if relevant for this package.
         os: [macos-latest, ubuntu-latest, windows-latest]
-        sdk: [2.16.0-124.0.dev, dev] # TODO(dacoharkes): Set to 2.16.0 after SDK release.
+        sdk: [2.16.0, dev] # TODO(dacoharkes): Set to 2.16.0 after SDK release.
     steps:
       - uses: actions/checkout@v2
       - uses: dart-lang/setup-dart@v1.0
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 05ccac5..a233981 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## 1.2.0
+
+This release requires Dart `2.16.0` or greater. 
+
 ## 1.2.0-dev.0
 
 Added common C integer types as ABI-specific integers. These common C integer
diff --git a/lib/src/c_type.dart b/lib/src/c_type.dart
index 67c5656..4fb8880 100644
--- a/lib/src/c_type.dart
+++ b/lib/src/c_type.dart
@@ -37,7 +37,7 @@
   Abi.iosArm64: Int8(),
   Abi.iosX64: Int8(),
   Abi.linuxArm: Uint8(),
-  Abi.linuxArm64: Int8(),
+  Abi.linuxArm64: Uint8(),
   Abi.linuxIA32: Int8(),
   Abi.linuxX64: Int8(),
   Abi.macosArm64: Int8(),
diff --git a/pubspec.yaml b/pubspec.yaml
index 7f15e92..5584baa 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,10 +1,10 @@
 name: ffi
-version: 1.2.0-dev.0
+version: 1.2.0
 homepage: https://github.com/dart-lang/ffi
 description: Utilities for working with Foreign Function Interface (FFI) code.
 
 environment:
-  sdk: '>=2.16.0-118.0.dev <3.0.0'
+  sdk: '>=2.16.0<3.0.0'
 
 dev_dependencies:
   test: ^1.16.0