You can install this specific version from NuGet.org or GitHub Packages using either of these commands:
Using the Package Manager Console:
PM> Install-Package MikaelDui.Upplysning.Client --Version 1.0.3
Using the .NET CLI:
dotnet add package MikaelDui.Upplysning.Client --version 1.0.3
But it's preferable to use floating versions, see the Microsoft Docs.