Make sure we don't try to use system minizip, as its not exactly the same as
the bundled version in 3rdparty/minizip

src/Exporters/ExportEPUB.cpp:146:85: error: use of undeclared identifier 'Z_NO_COMPRESSION'
    if (zipOpenNewFileInZip64(zfile, "mimetype", &fileInfo, NULL, 0, NULL, 0, NULL, Z_NO_COMPRESSION, 0, 0) != ZIP_OK) {
                                                                                    ^
src/Exporters/ExportEPUB.cpp:173:134: error: use of undeclared identifier 'Z_DEFAULT_STRATEGY'
        if (zipOpenNewFileInZip4_64(zfile, relpath.toUtf8().constData(), &fileInfo, NULL, 0, NULL, 0, NULL, Z_DEFLATED, 8, 0, 15, 8, Z_DEFAULT_STRATEGY, NULL, 0, 0x0b00, 1<<11, 0) != ZIP_OK) {

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -110,7 +110,6 @@ if (USE_SYSTEM_LIBS)
     MESSAGE(STATUS "Trying to use System Libraries...")
     find_package( ZLIB )
     find_package( PkgConfig )
-    find_package( MiniZip )
     pkg_check_modules( HUNSPELL hunspell )
     if ( NOT APPLE )
         pkg_check_modules( PCRE2 libpcre2-16 )