all: release v0.28.0 (#539)

CHANGES.md

diff --git a/CHANGES.md b/CHANGES.md
index 5ac4bc2..8a15d1b 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,14 @@
+# v0.28.0
+
+## Changes
+
+- gensupport:
+  - Retry the initial request for a media upload in the storage library only.
+- Various updates to autogenerated clients.
+
+_Please note:_ the release version is not indicative of an individual client's
+stability or version.
+
 # v0.27.0
 
 ## Changes