Fix: set accept_encoding to nil to use Typhoeus defaults.

[sahacky]

Problem

When using Faraday with the Typhoeus adapter, file download requests with specific content encoding types (particularly aws-chunked) were failing with Unrecognized or bad HTTP Content or Transfer-Encoding errors.

The root cause was that accept_encoding: '' explicitly disables encoding handling, which interferes with proper compression and content encoding processing by servers.

Solution

Changed accept_encoding: '' to accept_encoding: nil in the Typhoeus adapter. This allows Typhoeus to use default values and handle compression correctly while maintaining proper server communication.

Testing

✅ All existing tests pass

✅ Rubocop without offenses

✅ Backward compatibility maintained

✅ File downloads with various content encodings now work correctly

✅ Standard gzip/deflate compression handling preserved