fix: password prompt deleted - shell makefile for linux users

[louispaga]

Issue

resolves #57

Description

• Removed the database password prompt by generating a random password. The password is treated as sensitive by default. (see https://registry.terraform.io/providers/hashicorp/random/latest/docs/resources/password)
• Change from sh to bash the SHELL for GNU users. The default shell on GNU is sh and it does not include the command "source".

###Tests

• I deployed the infra and checked if the changes were saved.
• The changes within the makefile were just tested on GNU and it was ok. Maybe a deployment test on another OS is necessary. Will take care of this in the next few days.

[AlexisVLRT]

Hey, sorry for the super late review. Thanks for the contribution though, the code looks good !

Could you edit your PR message to indicate the issue you're resolving by adding resolves #XX to the message ? It helps for automation.
Also can you explicit what you did to test your feature ?

Thanks !