Don't run the installation script on windows

Windows is not a supported OS. Therefore, the installation script
shouldn't run when on this system.

This commit adds a check before the script runs. If the system is
Windows based, the installation won't run and a message will be shown.

.changesets/don-t-run-the-insallation-script-on-windows.md

@@ -0,0 +1,6 @@
+---
+bump: patch
+type: fix
+---
+
+When running the installation script on Microsoft Windows, some components threw an error. AppSignal doesn't support Windows, so the installation script won't run on Windows anymore. Preventing errors from raising.

lib/mix/tasks/appsignal.install.ex

@@ -2,7 +2,22 @@ defmodule Mix.Tasks.Appsignal.Install do
   use Mix.Task
   @shortdoc "Installs AppSignal into the current application"
 
-  def run([]) do
+  def run(args) do
+    case :os.type() do
+      {:win32, _} ->
+        """
+        We've detected that you're running Windows. Unfortunately, AppSignal does not support Windows at this time.
+        """
+        |> IO.puts()
+
+        exit(:shutdown)
+
+      _ ->
+        do_run(args)
+    end
+  end
+
+  defp do_run([]) do
     header()
 
     """
@@ -17,7 +32,7 @@ defmodule Mix.Tasks.Appsignal.Install do
     |> IO.puts()
   end
 
-  def run([push_api_key]) do
+  defp do_run([push_api_key]) do
     config = %{otp_app: otp_app(), active: true, push_api_key: push_api_key, request_headers: []}
     Application.put_env(:appsignal, :config, config)
     Appsignal.Config.initialize()