Prepare to publish a new version of dartfix

Change-Id: I9cf1cf3a135ffda24509f892b9039a88a40b9ee8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/169791
Reviewed-by: Devon Carew <devoncarew@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>

Author: bwilkerson

pkg/dartfix/CHANGELOG.md

@@ -1,3 +1,7 @@
+# 0.1.8
+* The dartfix package has been deprecated. The functionality has been moved to
+  the new `dart fix` command that's included in the SDK.
+
 # 0.1.7
 * Improve experimental non-nullable migration support.
 * Extract some nnbd migration implementation components from the dartfix

pkg/dartfix/pubspec.yaml

@@ -1,5 +1,5 @@
 name: dartfix
-version: 0.1.7
+version: 0.1.8
 description:
   A tool for migrating Dart source to newer versions of the Dart SDK
   and fixing common issues.