Increase ecm, cmake and qt requirements a bit

CMakeLists.txt

-cmake_minimum_required (VERSION 2.8.12 FATAL_ERROR)
+cmake_minimum_required (VERSION 3.16 FATAL_ERROR)
 
 project(mobipocket)
 
-find_package(ECM 1.3.0 REQUIRED NO_MODULE)
+find_package(ECM 5.68.0 REQUIRED NO_MODULE)
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${ECM_MODULE_PATH} )
 
 include(FeatureSummary)
@@ -14,7 +14,7 @@ include(KDEInstallDirs)
 include(KDECMakeSettings)
 include(KDECompilerSettings NO_POLICY_SCOPE)
 
-set(REQUIRED_QT_VERSION 5.4.0)
+set(REQUIRED_QT_VERSION 5.12.0)
 find_package(Qt5 ${REQUIRED_QT_VERSION} CONFIG REQUIRED Core Gui)
 
 ecm_setup_version("2.0.0"