refactor: adjust multicheckbox CSS for Django 4.0

Author: jerivas

mezzanine/core/static/mezzanine/css/admin/global.css

@@ -240,14 +240,18 @@ td, th, th a, label, .help, p.help {
     font-size: 13px !important;
 }
 /* mezzanine.core.fields.MultiChoiceField */
+.multicheckbox > * {
+    display: inline-flex;
+    margin: 0;
+    padding: 0;
+}
 .multicheckbox li {
     list-style-type: none;
-    float: left;
-    margin-right: 10px;
 }
-.multicheckbox li label {
+.multicheckbox label {
     width: auto;
     font-weight: normal;
+    margin-right: 10px;
 }
 .multicheckbox input {
     margin: -1px 6px 0 0;