Make tests synchronous #525

Job	Run time
Lint (ubuntu-latest, 1.17, 27)	1m 13s
Lint (ubuntu-latest, 1.17, 27)	1m 13s
Test Elixir 1.17, OTP 27, OS ubuntu-latest	35s
Test Elixir 1.17, OTP 27, OS ubuntu-latest	35s
Test Elixir 1.17, OTP 26, OS ubuntu-latest	37s
Test Elixir 1.17, OTP 26, OS ubuntu-latest	37s
Test Elixir 1.17, OTP 25, OS ubuntu-latest	30s
Test Elixir 1.17, OTP 25, OS ubuntu-latest	30s
Test Elixir 1.16, OTP 26, OS ubuntu-latest	35s
Test Elixir 1.16, OTP 26, OS ubuntu-latest	35s
Test Elixir 1.16, OTP 25, OS ubuntu-latest	33s
Test Elixir 1.16, OTP 25, OS ubuntu-latest	33s
Test Elixir 1.15, OTP 26, OS ubuntu-latest	38s
Test Elixir 1.15, OTP 26, OS ubuntu-latest	38s
Test Elixir 1.15, OTP 25, OS ubuntu-latest	34s
Test Elixir 1.15, OTP 25, OS ubuntu-latest	34s
Test Elixir 1.17, OTP 27, OS windows-2019	1m 57s
Test Elixir 1.17, OTP 27, OS windows-2019	1m 57s
Test Elixir 1.17, OTP 26, OS windows-2019	1m 39s
Test Elixir 1.17, OTP 26, OS windows-2019	2m 15s
Test Elixir 1.17, OTP 25, OS windows-2019	1m 59s
Test Elixir 1.17, OTP 25, OS windows-2019	1m 59s
Test Elixir 1.16, OTP 26, OS windows-2019	2m 33s
Test Elixir 1.16, OTP 26, OS windows-2019	3m 1s
Test Elixir 1.16, OTP 25, OS windows-2019	2m 24s
Test Elixir 1.16, OTP 25, OS windows-2019	2m 24s
Test Elixir 1.15, OTP 26, OS windows-2019	1m 41s
Test Elixir 1.15, OTP 26, OS windows-2019	1m 41s
Test Elixir 1.15, OTP 25, OS windows-2019	1m 41s
Test Elixir 1.15, OTP 25, OS windows-2019	1m 41s
	39m 22s

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