Don't add unnecessary exe suffix

Author: jtschuster

test/Microsoft.NET.Publish.Tests/GivenThatWeWantToPublishASingleFileApp.cs

@@ -1181,7 +1181,7 @@ public void It_codesigns_an_app_targeting_osx(string rid, bool? enableMacOSCodeS
                 .Pass();
 
             var publishDir = GetPublishDirectory(publishCommand, targetFramework, runtimeIdentifier: rid).FullName;
-            var singleFilePath = Path.Combine(publishDir, $"{testProject.Name}{Constants.ExeSuffix}");
+            var singleFilePath = Path.Combine(publishDir, testProject.Name);
 
             bool shouldBeSigned = enableMacOSCodeSign ?? CodesignsByDefault;