RPM build

Source/LibationFileManager/NullInteropFunctions.cs

@@ -15,6 +15,7 @@ namespace LibationFileManager
 		public void SetFolderIcon(string image, string directory) => throw new PlatformNotSupportedException();
         public void DeleteFolderIcon(string directory) => throw new PlatformNotSupportedException();
 		public bool CanUpgrade => throw new PlatformNotSupportedException();
+		public string ReleaseIdentifier => throw new PlatformNotSupportedException();
 		public Process RunAsRoot(string exe, string args) => throw new PlatformNotSupportedException();
 		public void InstallUpgrade(string updateBundle) => throw new PlatformNotSupportedException();
 	}