Support for Multiline values in env files

[Zehir]

Description

As a developper I would like to have multiline env variables to load bigger values like json or cert definition.

Suggested solution

Upgrade dotenv to version >= v15.0.0 because it's support it.
https://github.com/motdotla/dotenv#multiline-values

Alternative

The only alternative is to have a big unreadable line of data

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[bluwy]

Ref: #6783

[Zehir]

Thanks @bluwy