Add sip as dev requirement

Although net technically needed by Cura, our other Python binding
modules (such as pynest2d, pyArcus, pySavitar) might need it if
the need to be build on the host machine

Contributes to CURA-9365

requirements-dev.txt

@@ -1,2 +1,3 @@
 pytest
 pyinstaller
+sip==6.5.1