txt/obtainium.txt: point to apkpure.net

Apparently apkpure.com is down and https://github.com/ImranR98/Obtainium/blob/ed2f0f2c0c7d1523eacd5e32eb4d4fe9c14458da/lib/app_sources/apkpure.dart#L23 recognises .net also as an official domain. The site has a vague announcement on the subject

txt/obtainium.txt

@@ -1,6 +1,6 @@
-https://apkpure.com/android-system-webview/com.google.android.webview
-https://apkpure.com/beeper-unified-messenger/com.beeper.chat
-https://apkpure.com/trichrome-library/com.google.android.trichromelibrary
+https://apkpure.net/android-system-webview/com.google.android.webview
+https://apkpure.net/beeper-unified-messenger/com.beeper.chat
+https://apkpure.net/trichrome-library/com.google.android.trichromelibrary
 https://codeberg.org/Berker/keyoxide-flutter
 https://f-droid.org/packages/com.apps.adrcotfas.goodtime
 https://f-droid.org/packages/com.darshancomputing.BatteryIndicatorPro