Updating windows build constraints

pkg/guid is not windows specific, as it can run on Linux.
Build constraints on guid_windows and guid_nonwindows are redundant with
file names, but added for consistency.

Added missing build constraints.

Added Ubuntu to test matrix, along with windows 2022.

Signed-off-by: Hamza El-Saawy <hamzaelsaawy@microsoft.com>

pkg/guid/guid.go

@@ -1,5 +1,3 @@
-// +build windows
-
 // Package guid provides a GUID type. The backing structure for a GUID is
 // identical to that used by the golang.org/x/sys/windows GUID type.
 // There are two main binary encodings used for a GUID, the big-endian encoding,

pkg/guid/guid_nonwindows.go

@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 package guid

pkg/guid/guid_test.go

@@ -1,5 +1,3 @@
-// +build windows
-
 package guid
 
 import (

pkg/guid/guid_windows.go

@@ -1,3 +1,6 @@
+//go:build windows
+// +build windows
+
 package guid
 
 import "golang.org/x/sys/windows"