Update vendor (#1265)

vendor/github.com/slack-go/slack/slack.go

@@ -57,11 +57,12 @@ type authTestResponseFull struct {
 type ParamOption func(*url.Values)
 
 type Client struct {
-	token      string
-	endpoint   string
-	debug      bool
-	log        ilogger
-	httpclient httpClient
+	token         string
+	appLevelToken string
+	endpoint      string
+	debug         bool
+	log           ilogger
+	httpclient    httpClient
 }
 
 // Option defines an option for a Client
@@ -93,6 +94,11 @@ func OptionAPIURL(u string) func(*Client) {
 	return func(c *Client) { c.endpoint = u }
 }
 
+// OptionAppLevelToken sets an app-level token for the client.
+func OptionAppLevelToken(token string) func(*Client) {
+	return func(c *Client) { c.appLevelToken = token }
+}
+
 // New builds a slack client from the provided token and options.
 func New(token string, options ...Option) *Client {
 	s := &Client{