Update actions/checkout action to v4

package.json

@@ -16,7 +16,7 @@
     "url": "https://git.sp-codes.de/samuel-p/samuel-philipp.de"
   },
   "optionalDependencies": {
-    "browser-sync": "^3.0.2"
+    "browser-sync": "^2.29.3"
   },
   "devDependencies": {
     "@11ty/eleventy": "^2.0.1",
@@ -29,13 +29,13 @@
     "eleventy-plugin-rev": "^2.0.0",
     "eleventy-sass": "^2.2.4",
     "glob": "^10.3.10",
-    "minify": "^11.0.1",
+    "minify": "^10.5.2",
     "postcss": "^8.4.32",
     "sass": "^1.69.5",
     "uncss": "^0.17.3"
   },
   "dependencies": {
     "bootstrap": "^5.3.2",
-    "flag-icons": "^7.1.0"
+    "flag-icons": "^7.0.3"
   }
 }