stackdriver: fix test

pkg/api/pluginproxy/ds_auth_provider.go

@@ -4,10 +4,10 @@ import (
 	"bytes"
 	"context"
 	"fmt"
-	"html/template"
 	"net/http"
 	"net/url"
 	"strings"
+	"text/template"
 
 	m "github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/plugins"