Add zaporylie/composer-drupal-optimizations.

[unclegcb]

For the PR creator:

Check off the following boxes before asking someone to review this PR.

• [x] If this PR changes the composer.json file, is there accompanying text in the README.md file explaining that change? Seems unnecessary
• [x] Update the "How to test this branch" instructions below by replacing [the-branch] with the name of this branch, and [the-new-project] with an example project name.

What this PR does:

Adds zaporylie/composer-drupal-optimizations to the dev requirements to prevent PHP out of memory errors when running composer.

How to test this branch:

• [ ] If you haven't already, run the One time setup steps
• [ ] Run "composer install"
• [ ] Run "composer require drupal/leaflet" and confirm you don't get an out-of-memory error.

terminus build:project:create --team='United Philanthropy Forum' --org='United-Philanthropy-Forum' --visibility='private' --stability=dev "united-philanthropy-forum/km-starter-kit:dev-composer_drupal" kmc-composer

• [ ] Validate that a new site exists at https://dev-kmc-composer.pantheonsite.io
• [ ] Validate the repo exists at https://github.com/United-Philanthropy-Forum/kmc-composer
• [ ] Delete the test environment when you're done, by running terminus build:env:obliterate kmc-composer

[unclegcb]

@mariacha I'm not sure all that testing is necessary for this one.

[mariacha]

Agreed. Nice!