allow the 2.12 prerelease sdks (#64)

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52c3fb5..de8e4ca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 * Remove workaround for https://github.com/dart-lang/sdk/issues/43136, which is
   now fixed.
+* Allow prerelease versions of the 2.12 sdk.
 
 # 1.8.0-nullsafety.2
 

pubspec.yaml

diff --git a/pubspec.yaml b/pubspec.yaml
index 50450fc..2932d11 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,12 +1,12 @@
 name: source_span
-version: 1.8.0-nullsafety.3-dev
+version: 1.8.0-nullsafety.3
 
 description: A library for identifying source spans and locations.
 homepage: https://github.com/dart-lang/source_span
 
 environment:
   # This must remain a tight constraint until nnbd is stable
-  sdk: '>=2.11.0-0.0 <2.11.0'
+  sdk: '>=2.11.0-0.0 <2.12.0'
 
 dependencies:
   charcode: '>=1.2.0-nullsafety <1.2.0'
@@ -15,58 +15,4 @@
   term_glyph: '>=1.2.0-nullsafety <1.2.0'
 
 dev_dependencies:
-  test: ^1.6.0
-
-dependency_overrides:
-  async:
-    git: git://github.com/dart-lang/async.git
-  boolean_selector:
-    git: git://github.com/dart-lang/boolean_selector.git
-  charcode:
-    git: git://github.com/dart-lang/charcode.git
-  collection:
-    git: git://github.com/dart-lang/collection.git
-  js:
-    git:
-      url: git://github.com/dart-lang/sdk.git
-      path: pkg/js
-      ref: 2-10-pkgs
-  matcher:
-    git: git://github.com/dart-lang/matcher.git
-  meta:
-    git:
-      url: git://github.com/dart-lang/sdk.git
-      path: pkg/meta
-      ref: 2-10-pkgs
-  path:
-    git: git://github.com/dart-lang/path.git
-  pedantic:
-    git: git://github.com/dart-lang/pedantic.git
-  pool:
-    git: git://github.com/dart-lang/pool.git
-  source_maps:
-    git: git://github.com/dart-lang/source_maps.git
-  source_map_stack_trace:
-    git: git://github.com/dart-lang/source_map_stack_trace.git
-  stack_trace:
-    git: git://github.com/dart-lang/stack_trace.git
-  stream_channel:
-    git: git://github.com/dart-lang/stream_channel.git
-  string_scanner:
-    git: git://github.com/dart-lang/string_scanner.git
-  term_glyph:
-    git: git://github.com/dart-lang/term_glyph.git
-  test_api:
-    git:
-      url: git://github.com/dart-lang/test.git
-      path: pkgs/test_api
-  test_core:
-    git:
-      url: git://github.com/dart-lang/test.git
-      path: pkgs/test_core
-  test:
-    git:
-      url: git://github.com/dart-lang/test.git
-      path: pkgs/test
-  typed_data:
-    git: git://github.com/dart-lang/typed_data.git
+  test: ^1.16.0-nullsafety