Build: Update commons-net for FTP client to 3.11.1

Now that we can use java.time from core library desugaring.

app/build.gradle

@@ -174,9 +174,7 @@ dependencies {
     // Guava conflicts with com.google.guava:listenablefuture:1.0 pulled in by AndroidX Core
     implementation 'com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava'
     implementation 'com.takisoft.preferencex:preferencex:1.1.0'
-    // Commons Net 3.9.0 started using java.time.Duration in FTPClient.
-    //noinspection GradleDependency
-    implementation 'commons-net:commons-net:3.8.0'
+    implementation 'commons-net:commons-net:3.11.1'
     // LicensesDialog 2.2.0 pulls in androidx.webkit and uses setForceDark() instead of correctly
     // setting colors.
     //noinspection GradleDependency