use the correct mather for the surrogate pair code range

Author: hahn-kev

src/SIL.LCModel.Core/Text/TsStringSerializer.cs

@@ -188,7 +188,7 @@ public static string SerializeTsStringToXml(ITsString tss, ILgWritingSystemFacto
 			return xml.ToString();
 		}
 
-		private static readonly Regex InvalidXmlRegex = new Regex(@"[^\x09\x0A\x0D\x20-\uD7FF\uE000-\uFFFD\u10000-\u10FFFF]", RegexOptions.Compiled);
+		private static readonly Regex InvalidXmlRegex = new Regex(@"[^\x09\x0A\x0D\x20-\uD7FF\uE000-\uFFFD\p{Cs}]", RegexOptions.Compiled);
 		public static string StripInvalidXmlChars(string text)
 		{
 			// Remove characters not allowed in XML:

tests/SIL.LCModel.Core.Tests/Text/TsStringSerializerTests.cs

@@ -55,6 +55,7 @@ public void SerializeTsStringToXml_StripsInvalidControlCharacter()
 		[TestCase(" 𐰉 (dǒng)")]//Nushu script
 		[TestCase("𠔤野 (Nishino)")]//Japanese Kanji
 		[TestCase("𠮷野家 (Yóu yě jiā)")]//Historic Chinese
+		[TestCase("🦊")]//emoji
 		public void SerializeTsStringToXml_DoesNotStripValidCharacters(string word)
 		{
 			ITsString tss = TsStringUtils.MakeString(word, EnWS);