Upgrade to php 8.4 (#24)

* Added test script to composer.json #KDS-507

* Added php 8.4 to CI #KDS-507

Ensure that dot stuffing is done before encoding (#22)

* Added test with mesage body that breaks if dot stuffing is done before encoding. Changed `Writer::writeFiltered` to use `stream_filter_prepend`.

* Added comment since we have no assertions

Merge pull request #19 from kodus/bugfix/deprecation-warnings-on-preg…

…-match-calls

Fixed deprecation warnings from calling preg_match() with null values

Changed subject wording in test.

Merge pull request #17 from sunkan/support-psr-log-2-and-3

Add support for psr/log 2 and 3

Added missing return type to `SMTPDotStuffingFilter::filter` (#16)

Upgrade to PHP 8.1 (#14)

* Updated PHP requirements to >= 8.0

* Updated Codeception to ^5

* Enabled `SecureSocketCest::sendSMTPMessageOverSecureSocket` since it is functional, but added a stopgap in case SSL is not configured correctly since the actual error message is garbled

* Rewrote the development guidelines

* Removed Travis and added Github Actions

Fix HEREDOC in tests for php 7.3 (#13)

okay, so Travis wasn't ready for early testing with PHP 7.3

Merge pull request #9 from hanzi/secure-socket-connector-fix

Repair SecureSocketConnector