chore: minor refactor of webhook module

pkg/modules/webhook/client.go

@@ -16,9 +16,9 @@ import (
 type client struct {
 	url              string
 	method           string
-	errorURL         string
+	errorUrl         string
 	errorMethod      string
-	extraHTTPHeaders map[string]string
+	extraHttpHeaders map[string]string
 	startTime        time.Time
 
 	client *retryablehttp.Client
@@ -29,7 +29,7 @@ type client struct {
 func (c client) send(body io.Reader, headers map[string]string, erroed bool) error {
 	URL := c.url
 	if erroed {
-		URL = c.errorURL
+		URL = c.errorUrl
 	}
 
 	method := c.method
@@ -45,7 +45,7 @@ func (c client) send(body io.Reader, headers map[string]string, erroed bool) err
 	req.Header.Set("User-Agent", "Gotenberg")
 
 	// Extra HTTP headers are the custom headers from the user.
-	for key, value := range c.extraHTTPHeaders {
+	for key, value := range c.extraHttpHeaders {
 		req.Header.Set(key, value)
 	}