feat: add upgrade theme script

Author: phenix3443

upgrade-theme.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+hugo mod get github.com/razonyang/hugo-theme-bootstrap@master &&
+    hugo mod npm pack &&
+    npm update &&
+    git add go.mod go.sum package.json package-lock.json &&
+    git commit -m 'Update the theme'