chore(deps): update dependency gulp-imagemin to v8

Author: renovate[bot]

package.json

@@ -44,7 +44,7 @@
     "gulp-csso": "4.0.1",
     "gulp-gh-pages": "0.5.4",
     "gulp-htmlmin": "5.0.1",
-    "gulp-imagemin": "7.1.0",
+    "gulp-imagemin": "8.0.0",
     "gulp-minify": "3.1.0",
     "gulp-sourcemaps": "3.0.0",
     "gulp-typescript": "6.0.0-alpha.1",