No-op app update checks for Android < 8

This effectively makes it the last release for the older Android versions.

app/src/main/java/eu/kanade/tachiyomi/data/updater/AppUpdateChecker.kt

@@ -1,6 +1,7 @@
 package eu.kanade.tachiyomi.data.updater
 
 import android.content.Context
+import android.os.Build
 import eu.kanade.tachiyomi.BuildConfig
 import eu.kanade.tachiyomi.util.system.isInstalledFromFDroid
 import tachiyomi.core.util.lang.withIOContext
@@ -12,6 +13,11 @@ class AppUpdateChecker {
     private val getApplicationRelease: GetApplicationRelease by injectLazy()
 
     suspend fun checkForUpdate(context: Context, forceCheck: Boolean = false): GetApplicationRelease.Result {
+        // Disabling app update checks for older Android versions that we're going to drop support for
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.P) {
+            return GetApplicationRelease.Result.NoNewUpdate
+        }
+
         return withIOContext {
             val result = getApplicationRelease.await(
                 GetApplicationRelease.Arguments(