Do not use the imported Python3 library directly.

It just a hassle (need to search for Python3 downstream,
cannot be backwards compatible).

CMakeLists.txt

@@ -179,10 +179,10 @@ if (OPM_ENABLE_PYTHON)
   else()
     if (OPM_ENABLE_EMBEDDED_PYTHON)
       find_package(Python3 REQUIRED COMPONENTS Interpreter Development)
-      set(PYTHON_LIBRARIES Python3::Python)
       get_target_property(_lib_path Python3::Python IMPORTED_LOCATION)
       set(PYTHON_LIBRARY ${_lib_path})
-      list(APPEND opm-common_LIBRARIES ${PYTHON_LIBRARIES})
+      set(PYTHON_LIBRARIES {PYTHON_LIBRARY})
+      list(APPEND opm-common_LIBRARIES ${PYTHON_LIBRARY})
       set(PYTHON_INCLUDE_DIRS ${Python3_INCLUDE_DIRS})
     else()
       find_package(Python3 REQUIRED COMPONENTS Interpreter)

opm-common-prereqs.cmake

@@ -22,10 +22,4 @@ list(APPEND opm-common_DEPS
       # as the embedded one.
       "fmt 7.0.3"
 )
-if(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.12.0")
-  list(APPEND opm-common_DEPS
-    # Needed for the imported target Python3::Python
-    "Python3 COMPONENTS Interpreter Development"
-    )
-endif()
 find_package_deps(opm-common)