get the version info from a pro addin

pro-addin-version.cs

var myDocs = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
            var arcGisProLocation = Path.Combine(myDocs, "ArcGIS", "AddIns", "ArcGISPro");

            var attribute = (GuidAttribute) _assembly.GetCustomAttributes(typeof(GuidAttribute), true)[0];
            var proAddinFolder = $"{{{attribute.Value}}}";

            var addinFolder = Path.Combine(arcGisProLocation, proAddinFolder);
            if (!Directory.Exists(addinFolder))
                return null;

            // glob for *.esriAddinX
            var addins = Directory.GetFiles(addinFolder, "*.esriAddinX");

            if (!addins.Any())
                throw new ArgumentOutOfRangeException($"Could not find the addin in {addinFolder}");

            if (addins.Length > 1)
                throw new ArgumentOutOfRangeException($"Multiple esriAddinX files in {addinFolder}");

            var addin = addins.FirstOrDefault();

            var entry = ZipFile.OpenRead(addin)
                .Entries
                .FirstOrDefault(x => x.Name.Equals("config.daml", StringComparison.InvariantCultureIgnoreCase));

            if (entry == null)
                throw new ArgumentException("Could not find config.daml");

            var text = new string(
                new StreamReader(
                        entry
                            .Open(), Encoding.UTF8)
                    .ReadToEnd()
                    .ToArray());

            var xmlDoc = XDocument.Parse(text);

            var ns = XNamespace.Get("http://schemas.esri.com/DADF/Registry");
            var addInInfo = xmlDoc.Root?.Element(ns + "AddInInfo");
            if (addInInfo == null)
                throw new ArgumentException("could not find AddInInfo xml element");

            var name = addInInfo.Element(ns + "Name");

            return new VersionInformation(name?.Value, addInInfo.Attributes().Single(x => x.Name == "version").Value,
                addInInfo.Attributes().Single(x => x.Name == "desktopVersion").Value);