Change u_height type to float parameter

[Cyrilpop]

Here :

ansible_modules/plugins/modules/netbox_device_type.py

Line 213 in 2cb63a7

u_height=dict(required=False, type="int"),

This parameter is float type in netbox, so why not change to float here too ?
Some devices have a height like 1.5 U

[Cyrilpop]

I've done a PR here : #1200