CMake: replace FindPythonIntp with FindPython3

The earlier were deprecated since CMake 3.12.
Since CMake 3.27 this causes deprecation warnings.
Should be safe nowadays to require CMake 3.12.

Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.10)
+cmake_minimum_required(VERSION 3.12)
 cmake_policy(SET CMP0048 NEW)
 
 project(OpenVPN3-core VERSION 3)

client/CMakeLists.txt

@@ -16,8 +16,8 @@ if (${BUILD_SWIG_LIB})
  )
 
  add_core_dependencies(ovpnclilib)
- target_link_libraries(ovpnclilib ${PYTHON_LIBRARIES})
- target_include_directories(ovpnclilib PRIVATE ${PYTHON_INCLUDE_DIRS} ${CMAKE_CURRENT_SOURCE_DIR})
+ target_link_libraries(ovpnclilib ${Python3_LIBRARIES})
+ target_include_directories(ovpnclilib PRIVATE ${Python3_INCLUDE_DIRS} ${CMAKE_CURRENT_SOURCE_DIR})
 
  # Use proper python library name to generate _ovpncli.so/dylib/dll
  set_target_properties(ovpnclilib PROPERTIES OUTPUT_NAME "_ovpncli")

cmake/findswigdeps.cmake

@@ -1,11 +1,10 @@
-find_package(PythonInterp)
-find_package(PythonLibs)
+find_package(Python3 COMPONENTS Interpreter Development)
 
 FIND_PACKAGE(SWIG 3.0)
 
 # We test building this library with python instead of java since that is easier to do and both languages should work
 
-if (PYTHONLIBS_FOUND AND SWIG_FOUND)
+if (Python3_Development_FOUND AND SWIG_FOUND)
  if (NOT WIN32)
  set(BUILD_SWIG_LIB TRUE)
  elseif("${CMAKE_EXE_LINKER_FLAGS}" MATCHES "x64")