facts: add APIVersion constant

client/facts/facts.go

@@ -7,6 +7,8 @@ import (
 	"github.com/zcalusic/sysinfo"
 )
 
+const APIVersion string = "facts/v1alpha1"
+
 type FactsResponse struct {
 	APIVersion  string                  `json:"apiVersion"`
 	CPUInfo     sysinfo.CPU             `json:"cpu"`
@@ -24,7 +26,7 @@ func GetFacts(next http.Handler) http.Handler {
 
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		resp := FactsResponse{
-			APIVersion:  "v1",
+			APIVersion:  APIVersion,
 			CPUInfo:     si.CPU,
 			BoardInfo:   si.Board,
 			DeviceInfo:  si.Product,