feat: Custom composer options with the COMPOSER_FLAGS environment variable

[aguingand]

Summary

Related to #237

Deploy command generally doesn't need composer's "require-dev" dependencies. We can prevent installing these packages by adding the --no-dev option to composer install. This PR allows to add composer options in the following environment variable:

COMPOSER_FLAGS = "--no-dev"

There are other install options that may be useful depending on projects.

---

For us to review and ship your PR efficiently, please perform the following steps:

• Open a bug/issue before writing your code 🧑‍💻. This ensures we can discuss the changes and get feedback from everyone that should be involved. If you`re fixing a typo or something that`s on fire 🔥 (e.g. incident related), you can skip this step.
• Read the contribution guidelines 📖. This ensures your code follows our style guide and passes our tests.
• Update or add tests (if any source code was changed or added) 🧪
• Update the included software doc (if you updated included software) 📄
• Update or add documentation (if features were changed or added) 📝
• Make sure the status checks below are successful ✅

A picture of a cute animal (not mandatory, but encouraged)

[conventional-commit-lint-gcf]

🤖 I detect that the PR title and the commit message differ and there's only one commit. To use the PR title for the commit history, you can use Github's automerge feature with squashing, or use automerge label. Good luck human!

-- conventional-commit-lint bot
https://conventionalcommits.org/

[kitop]

Thanks for the contribution, @aguingand
Do you mind adding a test for this?

[aguingand]

@kitop done !