Bump version to 0.5.4

Change-Id: Ic602dd179a403427f078c48a3798d67986490b10

manifest.json

diff --git a/manifest.json b/manifest.json
index 62d9a4c..2a6aa49 100644
--- a/manifest.json
+++ b/manifest.json
@@ -2,7 +2,7 @@
   "manifest_version": 2,
   "name": "Gerrit UI Switcher",
   "description": "Easily switch between the current Gerrit UI and the new PolyGerrit UI",
-  "version": "0.5.3",
+  "version": "0.5.4",
   "background": {
     "scripts": [
       "background.js"