add reftag commandline argument

ModpackUpdater.Manager/ModpackInstaller.cs

@@ -21,6 +21,7 @@ public class ModpackInstaller(ModpackConfig updateConfig, ModpackInfo modpackInf
     public delegate void CheckingProgressUpdatedEventHandler(int toCheck, int processed);
 
     public ILogger Log { get; set; } = NullLogger.Instance;
+    public string? OverwriteRefTag { get; set; }
 
     private readonly HttpClient http = new();
     private readonly ModpackFactory factory = new();
@@ -32,13 +33,13 @@ public class ModpackInstaller(ModpackConfig updateConfig, ModpackInfo modpackInf
 
     private async Task<UpdateInfos> DownloadUpdateInfos()
     {
-        var content = await http.GetStringAsync(updateConfig.GetUpdateUrl());
+        var content = await http.GetStringAsync(updateConfig.GetUpdateUrl(overwriteRefTag: OverwriteRefTag));
         return UpdateInfos.Parse(content);
     }
 
     private async Task<InstallInfos> DownloadInstallInfos()
     {
-        var content = await http.GetStringAsync(updateConfig.GetInstallUrl());
+        var content = await http.GetStringAsync(updateConfig.GetInstallUrl(overwriteRefTag: OverwriteRefTag));
         return InstallInfos.Parse(content);
     }