Avoid time.DateOnly

It looks like the github action build environment for this repo uses
a go 1.19.x environment which does not have time.DateOnly. Replace
with local constant until this is upgraded.

(cherry picked from commit 22886dd)
(cherry picked from commit 5225542)
(cherry picked from commit fbaa1f1)
(cherry picked from commit 46091ed)

billing.go

@@ -31,6 +31,10 @@ type BillingUsageResponse struct {
 	httpHeader
 }
 
+// @todo remove this and replace w/ time.DateOnly once github build
+// environment is upgraded to a more recent go toolchain.
+const DateOnly = "2006-01-02"
+
 // currently the OpenAI usage API is not publicly documented and will explictly
 // reject requests using an API key authorization. however, it can be utilized
 // logging into https://platform.openai.com/usage and retrieving your session
@@ -43,8 +47,8 @@ var (
 // GetBillingUsage — API call to Get billing usage details.
 func (c *Client) GetBillingUsage(ctx context.Context, startDate time.Time,
 	endDate time.Time) (response BillingUsageResponse, err error) {
-	startDateArg := fmt.Sprintf("start_date=%v", startDate.Format(time.DateOnly))
-	endDateArg := fmt.Sprintf("end_date=%v", endDate.Format(time.DateOnly))
+	startDateArg := fmt.Sprintf("start_date=%v", startDate.Format(DateOnly))
+	endDateArg := fmt.Sprintf("end_date=%v", endDate.Format(DateOnly))
 	queryParams := fmt.Sprintf("%v&%v", startDateArg, endDateArg)
 	urlSuffix := fmt.Sprintf("%v?%v", billingUsageSuffix, queryParams)
 

billing_test.go

@@ -28,9 +28,9 @@ func TestBillingUsageAPIKey(t *testing.T) {
 
 	ctx := context.Background()
 
-	endDate, err := time.Parse(time.DateOnly, TestEndDate)
+	endDate, err := time.Parse(openai.DateOnly, TestEndDate)
 	checks.NoError(t, err)
-	startDate, err := time.Parse(time.DateOnly, TestStartDate)
+	startDate, err := time.Parse(openai.DateOnly, TestStartDate)
 	checks.NoError(t, err)
 
 	_, err = client.GetBillingUsage(ctx, startDate, endDate)
@@ -43,9 +43,9 @@ func TestBillingUsageSessKey(t *testing.T) {
 	server.RegisterHandler("/dashboard/billing/usage", handleBillingEndpoint)
 
 	ctx := context.Background()
-	endDate, err := time.Parse(time.DateOnly, TestEndDate)
+	endDate, err := time.Parse(openai.DateOnly, TestEndDate)
 	checks.NoError(t, err)
-	startDate, err := time.Parse(time.DateOnly, TestStartDate)
+	startDate, err := time.Parse(openai.DateOnly, TestStartDate)
 	checks.NoError(t, err)
 
 	resp, err := client.GetBillingUsage(ctx, startDate, endDate)
@@ -82,7 +82,7 @@ func handleBillingEndpoint(w http.ResponseWriter, r *http.Request) {
 
 	dailyCosts := make([]openai.DailyCostResponse, 0)
 
-	d, _ := time.Parse(time.DateOnly, TestStartDate)
+	d, _ := time.Parse(openai.DateOnly, TestStartDate)
 	d = d.Add(24 * time.Hour)
 	dailyCosts = append(dailyCosts, openai.DailyCostResponse{
 		TimestampRaw: float64(d.Unix()),