Build curaengine with C++20

Currently not possible to build everything with C++20
Due to incompatibility of libnest2d.

Contributes to CURA-8830

profiles/cura.jinja

@@ -10,6 +10,8 @@ compiler.cppstd=17
 {% elif compiler == 'apple-clang' %}compiler.libcxx=libc++
 {% elif compiler == 'Visual Studio' %}compiler.toolset=v143
 {% endif %}
+curaengine:compiler.cppstd=20
+
 [options]
 
 [env]