update sdk constraint to allow 2.11 dev (#84)

diff --git a/.travis.yml b/.travis.yml
index f3fbea2..4cc3a6a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -28,7 +28,7 @@
 
 # Only building master means that we don't run two builds for each pull request.
 branches:
-  only: [master, null_safety]
+  only: [master]
 
 # Incremental pub cache and builds.
 cache:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index badb6de..e762ceb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 1.0.0-dev
+## 1.0.0-nullsafety-dev
 
 * Migrate to null safety.
 
diff --git a/pubspec.yaml b/pubspec.yaml
index e718af4..3cc2b21 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: logging
-version: 1.0.0-dev
+version: 1.0.0-nullsafety-dev
 
 description: >-
   Provides APIs for debugging and error logging. This library introduces
@@ -11,7 +11,7 @@
 publish_to: none
 
 environment:
-  sdk: '>=2.10.0-0.0 <2.10.0'
+  sdk: '>=2.10.0-0.0 <2.11.0'
 
 dev_dependencies:
   pedantic: ^1.10.0-nullsafety