Fix dialyzer plts folder creation

[ghost]

Description

When we install the code repository for the first time, the priv/plts folder is not created.
Hence we should create it before to run mix dialyzer

Fixes #524

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Clone the repository and run mix dialyzer.
The priv/plts should be created and dialyzer run without error.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules