Removing old PHP versions from CI's style check step

[leocavalcante]

phplint was removed from jakzal/phpqa:php7.3 https://github.com/jakzal/toolbox/pull/398

This PR also drops 7.2 support as well.

Fixes CI error:

/entrypoint.sh: 6: exec: phplint: not found
Error: Process completed with exit code 127.

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This PR will neve be green because of #143

[deminy]

Added a new commit to fix syntax check under PHP 7.3.

References:

• https://github.com/jakzal/phpqa/issues/323
• https://github.com/swoole/ide-helper/commit/718db78eba3001c7dc3c64f842a81f7ff9071e85

[deminy]

@leocavalcante Could you please check my last commit and let me know if there are any concerns? Thanks

[leocavalcante]

Thanks @deminy ! Way better solution than just dropping it's support.