fix: avoid nil pointer error when debugging requests with no body (#176)

@cprivitere reported that cluster-api-provider-packet experiences nil
pointer errors when debugging is enabled and a request has no body. This
behavior seems to have started in v0.25.1, which introduced automatic
auth token redaction in debug output.

In order to redact the auth token without impacting the original
request, we were cloning the request object. In order to clone the
request body, we had to call `request.GetBody()`, but that function
causes a nil pointer error if the request body is nil.

This updates the auth token redaction code to temporarily overwrite the
auth token in the original request, rather than cloning the request &
its potentially-nil body.

templates/client.mustache

@@ -249,18 +249,22 @@ func parameterToJson(obj interface{}) (string, error) {
 // callAPI do the request.
 func (c *APIClient) callAPI(request *http.Request) (*http.Response, error) {
 	if c.cfg.Debug {
-		r := request.Clone(context.TODO())
-		r.Body, _ = request.GetBody()
-		h := r.Header
-		if len(h.Get("X-Auth-Token")) != 0 {
-			h.Set("X-Auth-Token", "**REDACTED**")
+		authToken, hasAuth := request.Header["X-Auth-Token"]
+		if hasAuth {
+			request.Header.Set("X-Auth-Token", "**REDACTED**")
 		}
 
-		dump, err := httputil.DumpRequestOut(r, true)
+		dump, err := httputil.DumpRequestOut(request, true)
+
+		if hasAuth {
+			request.Header["X-Auth-Token"] = authToken
+		}
+		
 		if err != nil {
 			return nil, err
 		}
 		log.Printf("\n%s\n", string(dump))
+
 	}
 
 	resp, err := c.cfg.HTTPClient.Do(request)