Log Message:
ibus-libpinyin: update to 1.15.8.

version 1.15.8
* bug fixes

version 1.15.7
* bug fixes

version 1.15.6
* bug fixes

version 1.15.5
* bug fixes

version 1.15.4
* Use libsoup3
* Update network dictionary
* Fix Caps Lock for English mode

version 1.15.3
* bug fixes

version 1.15.2
* bug fixes

version 1.15.1
* bug fixes

version 1.15.0
* bug fixes

version 1.14.91
* require libpinyin 2.7.91
* improve suggestion candidates
* improve English candidates
* support longer candidates
* support Legacy mode

version 1.13.1
* fix setup dialog

version 1.13.0
* bug fixes

version 1.12.92
* bug fixes

version 1.12.91
* enhance English input mode
* enhance Table input mode
* update setup dialog

version 1.12.1
* support compatibility display style
* remember cloud input
* bug fixes