Global

Program.cs

var path = @"";
var allVersions = new Dictionary<string, HashSet<string>>();
foreach (var file in Directory.EnumerateFiles(path, "*.*proj", SearchOption.AllDirectories))
{
	var doc = XDocument.Load(file);
	bool hasChanges = false;
	foreach (var reference in doc.XPathSelectElements("//PackageReference"))
	{
		hasChanges = true;
		var package = reference.Attribute("Include").Value;
		var versions = allVersions.GetValueOrDefault(package, new HashSet<string>());
		var versionAttribute = reference.Attribute("Version");
		versions.Add(versionAttribute.Value);
		allVersions[package] = versions;
		versionAttribute.Remove();
	}
	if (hasChanges)
	{
		File.WriteAllText(file, doc.ToString());
	}
}
Console.WriteLine(
	string.Join(Environment.NewLine,
	allVersions.ToDictionary(v => v.Key, v => v.Value.OrderDescending().First())
		.OrderBy(v => v.Key)
		.Select(v => $"<PackageVersion Include=\"{v.Key}\" Version=\"{v.Value}\" />")));