Update Elixir, Erlang, and Phoenix #409

Job	Run time
Test Linux script with bash shell	11m 29s
Test Linux script with fish shell	11m 39s
Install deps and compile	1m 17s
Check formatting using Prettier	7s
Test Linux script with zsh shell	11m 53s
Test macOS script with bash shell	7m 48s
Test macOS script with fish shell	7m 11s
Test macOS script with zsh shell	9m 58s
Credo	14s
Deps audit	11s
Format	15s
Hex audit	10s
Security check	12s
Dialyzer	2m 45s
Test	15s
Check unused deps	11s
Deploy preview app	20s
	1h 5m 55s

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