feature<*>: upgrade to .NET 5.0; use System.Text.Json instead of System.Xml; supports auto check update at startup

src/Git/Version.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Text.Json.Serialization;
+
+namespace SourceGit.Git {
+
+    /// <summary>
+    ///     Version information.
+    /// </summary>
+    public class Version {
+        [JsonPropertyName("id")]
+        public ulong Id { get; set; }
+        [JsonPropertyName("tag_name")]
+        public string TagName { get; set; }
+        [JsonPropertyName("target_commitish")]
+        public string CommitSHA { get; set; }
+        [JsonPropertyName("prerelease")]
+        public bool PreRelease { get; set; }
+        [JsonPropertyName("name")]
+        public string Name { get; set; }
+        [JsonPropertyName("body")]
+        public string Body { get; set; }
+        [JsonPropertyName("created_at")]
+        public DateTime CreatedAt { get; set; }
+    }
+}