Revert "Update *SdkVersion"

This reverts commit 5360cf4.

Changing this requires modification of the app. It is not required just
yet, so revert this for now.

Author: jmattheis

app/build.gradle

@@ -4,11 +4,11 @@ plugins {
 apply plugin: 'com.android.application'
 
 android {
-    compileSdkVersion 33
+    compileSdkVersion 30
     defaultConfig {
         applicationId "com.github.gotify"
         minSdkVersion 19
-        targetSdkVersion 33
+        targetSdkVersion 30
         versionCode 26
         versionName "2.4.0"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"