chore(deps): update dependency postgrex to ~> 0.20.0 (#119)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [postgrex](https://hex.pm/packages/postgrex) ([source](https://github.com/elixir-ecto/postgrex)) | prod | minor | `~> 0.19.0` -> `~> 0.20.0` |

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Reviewed-on: #119
Co-authored-by: renovate-bot <renovate-bot@dubas.dev>
Co-committed-by: renovate-bot <renovate-bot@dubas.dev>

mix.exs

@@ -49,7 +49,7 @@ defmodule Wabanex.MixProject do
       {:phoenix_view, "~> 2.0.0"},
       {:phoenix_live_dashboard, "~> 0.8.0"},
       {:plug_cowboy, "~> 2.7.0"},
-      {:postgrex, "~> 0.19.0"},
+      {:postgrex, "~> 0.20.0"},
       {:prom_ex, "~> 1.11.0"},
       {:sobelow, "~> 0.13", only: [:dev, :test], runtime: false},
       {:telemetry_metrics, "~> 1.1.0"},