Fix app packaging warning

PackagingOptions.jniLibs.useLegacyPackaging should be set to true because android:extractNativeLibs is set to "true" in AndroidManifest.xml.

https://monitor.f-droid.org/builds/log/com.termux/117

app/build.gradle

@@ -95,6 +95,13 @@ android {
             includeAndroidResources = true
         }
     }
+
+    packagingOptions {
+        jniLibs {
+            useLegacyPackaging true
+        }
+    }
+
 }
 
 dependencies {