kdeltachat: pin libdeltachat at 1.155.6
Otherwise kdeltachat fails to build with
/build/source/message.cpp: In member function 'void DcMessage::setFile(QString)':
/build/source/message.cpp:93:12: error: 'dc_msg_set_file' was not declared in this scope; did you mean 'dc_msg_get_file'?
93 | return dc_msg_set_file(m_message, utf8File.constData(), NULL);
| ^~~~~~~~~~~~~~~
| dc_msg_get_file