Fix remaining deprecations and follow best practice

composer.json

@@ -1,7 +1,4 @@
 {
-  "repositories": [
-    { "type": "composer", "url": "https://composer.typo3.org/" }
-  ],
   "name": "dpn/ep-reisen-web",
   "description" : "EP Reisen TYPO3 website package",
   "license": "GPL-2.0+",
@@ -21,8 +18,7 @@
     "kigkonsult/icalcreator": "^2.29",
     "league/csv": "^9.2",
     "league/period": "^4.9",
-    "lochmueller/staticfilecache": "^10.2",
-    "ssch/typo3-encore": "^2.0",
+    "ssch/typo3-encore": "^3.0",
     "symfony/http-client": "^4.3",
     "symfony/options-resolver": "^4.2",
     "symfony/property-access": "^4.3",
@@ -87,7 +83,7 @@
   "config": {
     "sort-packages": true,
     "platform": {
-      "php": "7.3.10"
+      "php": "7.4.13"
     }
   }
 }