Fix incorrect project page CSS class (#32510)

Otherwise milestone JS would run on this page and cause errors

Author: wxiaoguang

templates/repo/projects/new.tmpl

@@ -1,5 +1,5 @@
 {{template "base/head" .}}
-<div role="main" aria-label="{{.Title}}" class="page-content repository projects edit-project new milestone">
+<div role="main" aria-label="{{.Title}}" class="page-content repository projects edit-project new">
 	{{template "repo/header" .}}
 	<div class="ui container">
 	{{template "projects/new" .}}