Update dependencies (#886)

vendor/github.com/nlopes/slack/internal/errorsx/errorsx.go

@@ -0,0 +1,8 @@
+package errorsx
+
+// String representing an error, useful for declaring string constants as errors.
+type String string
+
+func (t String) Error() string {
+	return string(t)
+}

vendor/github.com/nlopes/slack/internal/timex/timex.go

@@ -0,0 +1,18 @@
+package timex
+
+import "time"
+
+// Max returns the maximum duration
+func Max(values ...time.Duration) time.Duration {
+	var (
+		max time.Duration
+	)
+
+	for _, v := range values {
+		if v > max {
+			max = v
+		}
+	}
+
+	return max
+}