Bump minimum supported Elixir version to 1.12

Related to #2777

Author: adriankumpf

mix.exs

@@ -5,7 +5,7 @@ defmodule TeslaMate.MixProject do
     [
       app: :teslamate,
       version: version(),
-      elixir: "~> 1.11",
+      elixir: "~> 1.12",
       elixirc_paths: elixirc_paths(Mix.env()),
       compilers: [:gettext] ++ Mix.compilers(),
       start_permanent: Mix.env() == :prod,

website/docs/installation/debian.md

@@ -24,7 +24,7 @@ Source: [postgresql.org/download](https://www.postgresql.org/download/)
 </details>
 
 <details>
-  <summary>Elixir (v1.11+)</summary>
+  <summary>Elixir (v1.12+)</summary>
 
 ```bash
 wget https://packages.erlang-solutions.com/erlang-solutions_2.0_all.deb && sudo dpkg -i erlang-solutions_2.0_all.deb

website/docs/installation/freebsd.md

@@ -41,7 +41,7 @@ pkg install erlang
 </details>
 
 <details>
-  <summary>Elixir (v1.11+)</summary>
+  <summary>Elixir (v1.12+)</summary>
 
 Unfortunately the Elixir part is not well updated in FreeBSD ports.
 Hence the latest supported version for Erlang 21 (latest in FreeBSD ports)