mignified assets for prod

sites/all/themes/custom/edlptheme/package.json

@@ -8,7 +8,7 @@
   "homepage": "https://encyclopediedelaparole.org",
   "devDependencies": {
     "gulp": "latest",
-    "gulp-autoprefixer": "latest",
+    "gulp-autoprefixer": "^5.0.0",
     "gulp-concat": "latest",
     "gulp-cssmin": "latest",
     "gulp-if": "^2.0.2",
@@ -16,7 +16,7 @@
     "gulp-json-to-sass": "latest",
     "gulp-json2js": "latest",
     "gulp-rename": "latest",
-    "gulp-sass": "latest",
+    "gulp-sass": "^4.0.1",
     "gulp-strip-debug": "^3.0.0",
     "gulp-svgmin": "^1.2.4",
     "gulp-util": "latest",