Log Message:
dillo: update to 3.1.1

- Disable TLSv1.3 in Mbed TLS 3.6.0 until it is supported.
- Add workaround for Cygwin and OpenSSL with --disable-threaded-dns.
- Fix distcheck when HTML tests are enabled.
- Fix an OpenSSL bug when the server closes the connection
  prematurely and SSL_get_error() returns SSL_ERROR_ZERO_RETURN.
- Gracefully handle warnings from PNG images.