issue 2117: fix another lint

Signed-off-by: Linh Luong <bo17age@gmail.com>

pkg/osutil/user.go

@@ -35,8 +35,10 @@ var (
 // regexUsername matches user and group names to be valid for `useradd`.
 // `useradd` allows names with a trailing '$', but it feels prudent to map those
 // names to the fallback user as well, so the regex does not allow them.
-var regexUsername = regexp.MustCompile("^[a-z_][a-z0-9_-]*$")
-var notAllowedUsernameRegex = regexp.MustCompile(`^admin$`)
+var (
+	regexUsername           = regexp.MustCompile("^[a-z_][a-z0-9_-]*$")
+	notAllowedUsernameRegex = regexp.MustCompile(`^admin$`)
+)
 
 // regexPath detects valid Linux path.
 var regexPath = regexp.MustCompile("^[/a-zA-Z0-9_-]+$")