>> Are you sure Sigil depends on Qt5?
CMake Error at src/Sigil/CMakeLists.txt:38 (find_package):
By not providing "FindQt5Core.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "Qt5Core", but
CMake did not find one.
Could not find a package configuration file provided by "Qt5Core" with any
of the following names:
Qt5CoreConfig.cmake
qt5core-config.cmake
Add the installation prefix of "Qt5Core" to CMAKE_PREFIX_PATH or set
"Qt5Core_DIR" to a directory containing one of the above files. If
"Qt5Core" provides a separate development package or SDK, be sure it has
been installed.