[fix] LESS sourcemaps broken in less-plugin-clean-css v1.6.0

The ``less-plugin-clean-css`` lacks some maintenance: the sourcemaps are broken
since v1.6.0 (08/2024) [1]

- [1] less/less-plugin-clean-css#42

Closes: searxng#4143

Signed-off-by: Markus Heiser <[email protected]>

Author: return42

searx/static/themes/simple/gruntfile.js

@@ -119,9 +119,6 @@ module.exports = function (grunt) {
       production: {
         options: {
           paths: ["less"],
-          plugins: [
-            new (require('less-plugin-clean-css'))()
-          ],
           sourceMap: true,
           sourceMapURL: (name) => { const s = name.split('/'); return s[s.length - 1] + '.map'; },
           outputSourceFiles: true,

searx/static/themes/simple/package-lock.json

@@ -14,7 +14,6 @@
     "grunt-xmlmin": "^0.1.8",
     "ionicons": "^7.4.0",
     "less": "^4.2.1",
-    "less-plugin-clean-css": "^1.6.0",
     "sharp": "^0.33.5",
     "stylelint": "^16.12.0",
     "stylelint-config-standard": "^36.0.0",