Fix unexpected crash during SSL tests

[paulo-ferraz-oliveira]

Crash (didn't affect tests, but gave off the impression something was wrong) was:

=ERROR REPORT==== 29-Oct-2020::11:08:45 ===
Elli request (pid #Port<0.86655>) unexpectedly crashed:
shutdown

=ERROR REPORT==== 29-Oct-2020::11:08:45 ===
Elli request (pid <0.396.0>) unexpectedly crashed:
{shutdown,{gen_statem,call,[<0.437.0>,{recv,0,60000},infinity]}}

[paulo-ferraz-oliveira]

In OTP 20.3, at least, it did make 1 test fail, though.

[coveralls]

Coverage decreased (-0.3%) to 75.546% when pulling 4b633252436da3aaa146849ac96c2376c79c4de7 on paulo-ferraz-oliveira:fix/unexpected_test_crash into 968afee385f46c053fd46858713261db7dc03af4 on elli-lib:main.

[coveralls]

Coverage decreased (-0.3%) to 75.546% when pulling 4b633252436da3aaa146849ac96c2376c79c4de7 on paulo-ferraz-oliveira:fix/unexpected_test_crash into 968afee385f46c053fd46858713261db7dc03af4 on elli-lib:main.

[paulo-ferraz-oliveira]

Now that I see the tests failing in Travis CI, executing them locally shows that "sometimes" they fail on OTP 23. Might it be a timing issue?

[paulo-ferraz-oliveira]

@tsloughter: is this OK for merge?

[tsloughter]

Ah yea. One sec, let me just rerun travis once more.

[tsloughter]

Maybe I'll finally move this to github actions soon...

[yurrriq]

relates to #90