Improved: type="text/css" was missing on a call to <<link rel="styles…

…heet/less>>

This was reported by OWASP ZAP: "The Content-Type header is missing or empty."
Considered a low vulnerability

themes/rainbowstone/template/includes/Header.ftl

@@ -46,7 +46,7 @@ under the License.
         <link rel="stylesheet/less" href="<@ofbizContentUrl>${StringUtil.wrapString(styleSheet)}</@ofbizContentUrl>" type="text/css"/>
     </#list>
 </#if>
-        <link rel="stylesheet/less" href="<@ofbizContentUrl>/rainbowstone/${visualTheme.visualThemeId?replace("_","-")?lower_case}.less</@ofbizContentUrl>"/>
+        <link rel="stylesheet/less" href="<@ofbizContentUrl>/rainbowstone/${visualTheme.visualThemeId?replace("_","-")?lower_case}.less</@ofbizContentUrl>" type="text/css"/>
 <#if layoutSettings.VT_HDR_JAVASCRIPT?has_content>
     <#list layoutSettings.VT_HDR_JAVASCRIPT as javaScript>
         <script src="<@ofbizContentUrl>${StringUtil.wrapString(javaScript)}</@ofbizContentUrl>" type="application/javascript"></script>