Use ssl:handshake/2 in test server on Erlang 21+ versions

[nickva]

ssl:ssl_acceppt is deprecated.

We use the OTP_RELEASE define which exists on OTP 21+ only.

[nickva]

Tested with:

% asdf shell erlang 20.3.8.26
% rebar eunit
...
======================== EUnit ========================
module 'ibrowse_test'
module 'ibrowse'
  module 'ibrowse_tests'
    ibrowse_tests: running_server_fixture_test_ (Simple request can be honored)...[0.334 s] ok
    ibrowse_tests: running_server_fixture_test_ (Slow server causes timeout)...[5.001 s] ok
    ibrowse_tests: running_server_fixture_test_ (Pipeline depth goes down with responses)...[2.001 s] ok
    ibrowse_tests: running_server_fixture_test_ (Pipelines refill)...[4.002 s] ok
    ibrowse_tests: running_server_fixture_test_ (Timeout closes pipe)...[7.002 s] ok
    ibrowse_tests: running_server_fixture_test_ (Requests are balanced over connections)...[2.002 s] ok
    ibrowse_tests: running_server_fixture_test_ (Pipeline too small signals retries)...[2.007 s] ok
    ibrowse_tests: running_server_fixture_test_ (Dest status can be gathered)...[2.002 s] ok
    [done in 40.438 s]
  [done in 40.438 s]
module 'ibrowse_socks_server'
module 'ibrowse_http_client'
module 'ibrowse_app'
module 'ibrowse_sup'
module 'ibrowse_lb'
module 'ibrowse_load_test'
module 'ibrowse_lib'
  ibrowse_lib_tests: parse_urls_test_ (module 'ibrowse_lib_tests')...ok
  [done in 0.003 s]
module 'ibrowse_socks5'
module 'ibrowse_test_server'
=======================================================
  All 9 tests passed.

Then

% asdf shell erlang 23.3.2
 % rebar eunit
==> ibrowse (eunit)
...
======================== EUnit ========================
module 'ibrowse_test'
module 'ibrowse'
  module 'ibrowse_tests'
    ibrowse_tests: fun.simple_request (Simple request can be honored)...[0.019 s] ok
    ibrowse_tests: fun.slow_server_timeout (Slow server causes timeout)...[5.002 s] ok
    ibrowse_tests: fun.pipeline_depth (Pipeline depth goes down with responses)...[2.001 s] ok
    ibrowse_tests: fun.pipeline_refill (Pipelines refill)...[4.002 s] ok
    ibrowse_tests: fun.closing_pipes (Timeout closes pipe)...[7.002 s] ok
    ibrowse_tests: fun.balanced_connections (Requests are balanced over connections)...[2.001 s] ok
    ibrowse_tests: fun.small_pipeline (Pipeline too small signals retries)...[2.005 s] ok
    ibrowse_tests: fun.status (Dest status can be gathered)...[2.001 s] ok
    [done in 40.095 s]
  [done in 40.095 s]
module 'ibrowse_socks_server'
module 'ibrowse_http_client'
module 'ibrowse_app'
module 'ibrowse_sup'
module 'ibrowse_lb'
module 'ibrowse_load_test'
module 'ibrowse_lib'
  ibrowse_lib_tests: fun.parse_urls (module 'ibrowse_lib_tests')...ok
  [done in 0.003 s]
module 'ibrowse_socks5'
module 'ibrowse_test_server'
=======================================================
  All 9 tests passed.

[nickva]

Thank you!