Releasing createsend-php

Requirements

Increment the CS_REST_WRAPPER_VERSION constant in the class/base_classes.php file, ensuring that you use Semantic Versioning.
Add an entry to HISTORY.md which clearly explains the new release.
Install development dependencies and ensure that tests pass locally:
```
composer install --dev
cd tests && php all_tests.php && cd ..
```
Commit your changes:
```
git commit -am "Version X.Y.Z"
```
Tag the new version:
```
git tag -a vX.Y.Z -m "Version X.Y.Z"
```
Push your changes to GitHub, including the tag you just created:
```
git push origin master --tags
```
Ensure that all tests pass.

There is a GitHub service hook for the Packagist PHP package repository, which is configured to update the createsend-php package when new tags are pushed to GitHub.

So there are no further steps to releasing the module. You should now see the latest version of the module listed on Packagist. All done!