build: use pwsh for release:package on Windows

[ShGKme]

☑️ Resolves

• ~~⚠️ Waiting for the release~~
• After https://github.com/nextcloud/talk-desktop/pull/602 release:package doesn't work on Windows. Manual setting pwsh (modern PowerShell v7) was replaced with usePowerShell that uses old unsupported and yet default one PowerShell v5 instead of new PowerShell v7+.

At line:1 char:24
+ npm run package:windows && npm run make:windows; exit $LastExitCode
+                         ~~
The token '&&' is not a valid statement separator in this version.
    + CategoryInfo          : ParserError: (:) [], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : InvalidEndOfLine

This PR sets up pwsh with new usePwsh from [email protected].