Setting an execution policy to RemoteSigned or Unrestricted should work. It must be changed under an administrator mode via a PowerShell console. Be aware that changes will be applied according to the bit version of the PowerShell console, so 32bit or 64 bit. So if you want to install a package in Visual Studio (32 bit version) which requires a specific policy you should change settings of the policy via PowerShell (x86).
The command in PowerShell (as administrator) to set the policy to unrestricted (as noted by @Gabriel in the comments) is:
start-job { Set-ExecutionPolicy Unrestricted } -RunAs32 | wait-job | Receive-Job
Having set the policy to unrestricted, you will want to set the policy back to its original after the install is complete.
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