fix(makexrsys): get version

Author: xrgzs

makexrsys.ps1

@@ -121,9 +121,9 @@ switch ($makeversion) {
         $obj = (Invoke-RestMethod https://c.xrgzs.top/OSList.json).'【更新】7_SP1_IE11_自选_64位_无驱动_原版无接管'
         $osurl = $obj.osurl2
         $osfile = $obj.osfile
-        $osindex = 3
+        $osindex = 4
         $osver = '7'
-        $osversion = ($obj.osfile.Substring(0, $obj.osfile.IndexOf('.',5)))
+        $osversion = ($obj.osfile -split '_')[-2]
         $osarch = 'x64'
         $sysver = "XRSYS_Win7_SP2_Pro_x64_CN_Full"
         $sysvercn = "潇然系统_Win7_SP2_专业_x64_完整"