Update to the latest pub

Brings in fix for https://github.com/dart-lang/pub/issues/1919

Change-Id: Ied08a3c4b9a61879bed33c0bf15c800690bf341d
Reviewed-on: https://dart-review.googlesource.com/60148
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Nate Bosch <nbosch@google.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index dd93176..f8e4540 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,8 @@
 
 #### Pub
 
+* Fix an error which prevented `pub publish` due to the package validation.
+
 #### Other Tools
 
 ### Core library changes
diff --git a/DEPS b/DEPS
index 74ce5d0..94230ce 100644
--- a/DEPS
+++ b/DEPS
@@ -110,7 +110,7 @@
   "ply_rev": "604b32590ffad5cbb82e4afef1d305512d06ae93",
   "pool_tag": "1.3.4",
   "protobuf_tag": "0.7.1",
-  "pub_rev": "881a0c3fbe63af07dd043b3f5e6cbe74eacb377c",
+  "pub_rev": "8b9526c915bf21627a20cd0104cb6c2be25a879f",
   "pub_semver_tag": "1.4.1",
   "quiver_tag": "5aaa3f58c48608af5b027444d561270b53f15dbf",
   "resource_rev":"af5a5bf65511943398146cf146e466e5f0b95cb9",