Update phoenix dependency to allow versions >= 1.7.6 and < 1.9.0

Author: Flo0807

mix.exs

@@ -55,7 +55,7 @@ defmodule Backpex.MixProject do
       {:money, "~> 1.13"},
 
       # phoenix
-      {:phoenix, "~> 1.7"},
+      {:phoenix, ">= 1.7.6 and < 1.9.0"},
       {:phoenix_html, "~> 4.1"},
       {:phoenix_html_helpers, "~> 1.0"},
       {:phoenix_live_view, "~> 1.0"},