Bump libzip to 1.7.3 and go back to mingw

[grendello]

Context: https://libzip.org/news/release-1.7.3.html Context: https://libzip.org/news/release-1.7.2.html Context: https://libzip.org/news/release-1.7.1.html Context: https://libzip.org/news/release-1.7.0.html

Upstream changes:

• Add support for encrypting using traditional PKWare encryption.
• Add zip_compression_method_supported().
• Add zip_encryption_method_supported().
• Add the ZIP_SOURCE_GET_FILE_ATTRIBUTES source command.
• Refactor stdio file backend.
• Add CMake find_project() support.
• Restore LIBZIPVERSION{MAJOR,MINOR,MICRO} symbols.
• Fixes warnings reported by PVS-Studio.
• Add LIBZIP_DO_INSTALL build setting to make it easier to use libzip as subproject.
• Fixes for the CMake find_project() files.
• libzip moved to the CMake libzip:: NAMESPACE.
• CMake usage best practice cleanups.
• Support cmake < 3.17 again.
• Fix pkgconfig file (regression in 1.7.2).

Windows libzip DLL is again built with mingw