chore(deps): update dependency phoenix to ~> 1.8.0

Author: renovate[bot]

mix.exs

@@ -68,7 +68,7 @@ defmodule Librecov.Mixfile do
       {:credo, "~> 1.4", only: [:dev, :test], runtime: false},
       {:dialyxir, "~> 1.0", only: [:dev, :test], runtime: false},
       {:jason, "~> 1.0"},
-      {:phoenix, "~> 1.6.0-rc.0", override: true},
+      {:phoenix, "~> 1.8.0", override: true},
       {:phoenix_html, "~> 3.0", override: true},
       {:phoenix_ecto, "~> 4.4"},
       {:ecto_sql, "~> 3.7"},