Fix explicit NuGet version tool corrupting package

UTF-16 in the nuspec won't load with NuGet, so force it to UTF-8.

tools/Explicit.NuGet.Versions/Program.cs

@@ -41,7 +41,7 @@ private static void UpdateNuspecManifestContent(Dictionary<string, NuspecContent
 				SetPackageDepencyVersionsToBeExplicitForXmlDocument(nuspecXmlDocument, dependencyNugetId);
 
 				string updatedNuspecXml;
-				using (var writer = new StringWriter(new StringBuilder()))
+				using (var writer = new StringWriterWithEncoding(Encoding.UTF8))
 				using (var xmlWriter = new XmlTextWriter(writer) { Formatting = Formatting.Indented })
 				{
 					nuspecXmlDocument.Save(xmlWriter);
@@ -60,7 +60,9 @@ private static void SetPackageDepencyVersionsToBeExplicitForXmlDocument(XmlDocum
 			    {
 				    var currentVersion = node.Attributes["version"].Value;
 					if (!node.Attributes["version"].Value.StartsWith("[") && !node.Attributes["version"].Value.EndsWith("]"))
+					{
 						node.Attributes["version"].Value = $"[{currentVersion}]";
+					}
 			    }
 		    });
 	    }
@@ -102,4 +104,19 @@ private static void WalkDocumentNodes(XmlNodeList nodes, Action<XmlNode> callbac
 		    }
 	    }
 	}
-}
+
+	public sealed class StringWriterWithEncoding : StringWriter
+	{
+		private readonly Encoding encoding;
+
+		public StringWriterWithEncoding(Encoding encoding)
+		{
+			this.encoding = encoding;
+		}
+
+		public override Encoding Encoding
+		{
+			get { return encoding; }
+		}
+	}
+}