Ubuntu 18.04 has moved to using libcurl4 instead of libcurl3. Even if both verison of the curl bianries and libraries are comaptible, there is a packaging issue that disallows packages using libcurl3 such as powershell to coexist with others that need libcurl4 such as cmake. Please relase powershell for Ubuntu 18.04 a.k.a bionic or people will be getting nasty surpirises next week just liek I did whe I upgraded early.