[release] Prepare changelog for 2.0.0-dev.54.0

TBR=sortie@google.com

Change-Id: I42a914ba39a6744b1940639ce4833f8869ca9a6f
Reviewed-on: https://dart-review.googlesource.com/54381
Reviewed-by: Alexander Thomas <athom@google.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0758d2a..cc2f791 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,10 +14,16 @@
 
 #### Pub
 
-* Retry on 500 errors from the pub server.
-
 #### Other Tools
 
+## 2.0.0-dev.54.0
+
+### Tool Changes
+
+#### Pub
+
+* Retry on 500 errors from the pub server.
+
 ## 2.0.0-dev.53.0
 
 ## 2.0.0-dev.52.0