message: Use PNG logo
diff: # Neqo, an Implementation of QUIC written in Rust
  -![neqo logo](https://github.com/mozilla/neqo/raw/master/neqo.svg "neqo logo")
  +![neqo logo](https://github.com/mozilla/neqo/raw/master/neqo.png "neqo logo")
  To run test http 0.9 programs (neqo-client and neqo-server):
  