chore(deps) Update dependency gulp-purgecss to v7 (#607)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

package.json

@@ -41,7 +41,7 @@
     "gulp-concat": "2.6.1",
     "gulp-cssnano": "2.1.3",
     "gulp-postcss": "10.0.0",
-    "gulp-purgecss": "6.0.0",
+    "gulp-purgecss": "7.0.2",
     "gulp-rename": "2.0.0",
     "gulp-replace": "^1.1.4",
     "gulp-sass": "5.1.0",
@@ -164,7 +164,7 @@
       "unicorn/prefer-at": "warn"
     }
   },
-  "version": "3.15.21",
+  "version": "3.15.22",
   "dependencies": {
     "sass": "^1.63.6"
   }