build: bump version to 3.15.4 (#966)

Signed-off-by: yxxhero <aiopsclub@163.com>

Author: yxxhero

plugin.yaml

@@ -1,7 +1,7 @@
 name: diff
 # Version is the version of Helm plus the number of official builds for this
 # plugin
-version: "3.15.3"
+version: "3.15.4"
 usage: "Preview helm upgrade changes as a diff"
 description: "Preview helm upgrade changes as a diff"
 useTunnel: true