Bring in the latest pub.

CHANGELOG.md

Index: CHANGELOG.md
diff --git a/CHANGELOG.md b/CHANGELOG.md
index fd8d19c4a7b5d5071e2dc17d0395fbb238c3a08c..2262af74187a2348bee543b385fca4de64af44b1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -127,6 +127,11 @@
     the context of the `flutter` executable, and when the Flutter SDK contains a
     package with the given name whose version matches the constraint.
 
+  * Added a `--no-packages-dir` flag to `pub get`, `pub upgrade`, and `pub
+    downgrade`. When this flag is passed, pub will not generate a `packages/`
+    directory, and will remove that directory and any symlinks to it if they
+    exist. Note that this replaces the unsupported `--no-package-symlinks` flag.
+
   * `tar` files on Linux are now created with `0` as the user and group IDs.
     This fixes a crash when publishing packages while using Active Directory.