update patch version for new build artifacts

Author: acalejos

lib/exgboost.ex

@@ -16,7 +16,7 @@ defmodule EXGBoost do
   ```elixir
   def deps do
   [
-    {:exgboost, "~> 0.2.0"}
+    {:exgboost, "~> 0.2.1"}
   ]
   end
   ```

mix.exs

@@ -1,6 +1,6 @@
 defmodule EXGBoost.MixProject do
   use Mix.Project
-  @version "0.2.0"
+  @version "0.2.1"
 
   def project do
     [

notebooks/iris_classification.livemd

@@ -2,7 +2,7 @@
 
 ```elixir
 Mix.install([
-  {:exgboost, "~> 0.2"},
+  {:exgboost, "~> 0.2.1"},
   {:nx, "~> 0.5"},
   {:scidata, "~> 0.1"},
   {:scholar, "~> 0.1"}