Add tests for ServerVersion.Empty.

Author: bgrainger

src/MySqlConnector/Core/ServerVersion.cs

@@ -55,6 +55,6 @@ public ServerVersion(ReadOnlySpan<byte> versionString)
 	private ServerVersion()
 	{
 		OriginalString = "";
-		Version = new Version(0, 0);
+		Version = new();
 	}
 }

tests/MySqlConnector.Tests/ServerVersionTests.cs

@@ -7,6 +7,15 @@ namespace MySqlConnector.Tests;
 
 public class ServerVersionTests
 {
+	[Fact]
+	public void Empty()
+	{
+		var empty = ServerVersion.Empty;
+		Assert.Equal("", empty.OriginalString);
+		Assert.Equal(new Version(0, 0), empty.Version);
+		Assert.False(empty.IsMariaDb);
+	}
+
 	[Theory]
 	[InlineData("5.5.5-10.1.38-MariaDB-1~bionic", "10.1.38", true)]
 	[InlineData("5.5.5-10.2.13-MariaDB", "10.2.13", true)]