dio Files

## What's new

• Fix response stream not propagating backpressure to the underlying socket. When a consumer paused the stream, the source subscription was never paused, so the network kept buffering response data into memory, risking OOM on constrained platforms.
• Make the badCertificateCallback pinning test deterministic by pinning a fingerprint that cannot match the served certificate, instead of relying on badssl.com hosts serving different certificates.
• Fix NoSuchMethodError when using a class that implements Interceptor instead of extends Interceptor. The interceptor pipeline was calling private dispatch methods that only exist on Interceptor subclasses, breaking any class using interface implementation.