Add app update broadcast receiver

So that notifications are also restored after app upgrade

uhabits-android/src/main/AndroidManifest.xml

@@ -217,6 +217,14 @@
             </intent-filter>
         </receiver>
 
+        <receiver
+            android:name=".receivers.UpdateReceiver"
+            android:exported="true">
+            <intent-filter>
+                <action android:name="android.intent.action.MY_PACKAGE_REPLACED" />
+            </intent-filter>
+        </receiver>
+
         <receiver android:name=".receivers.WidgetReceiver"
             android:exported="true"
             android:permission="false">

uhabits-android/src/main/java/org/isoron/uhabits/receivers/UpdateReceiver.kt

@@ -0,0 +1,14 @@
+package org.isoron.uhabits.receivers
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.util.Log
+
+class UpdateReceiver : BroadcastReceiver() {
+
+    override fun onReceive(context: Context, intent: Intent) {
+        // Dummy receiver, relevant code is executed through HabitsApplication.
+        Log.d("UpdateReceiver", "Update receiver called.")
+    }
+}