fix: change pnpm version due to pnpm bug

[herrardo]

Pull request template

Set pnpm version to 8.6.0 at Github actions to be installed, because of this bug:
pnpm/pnpm#6991

Motivation and context

Avoid this bug pnpm/pnpm#6991

• Dependencies. If any, specify:
• Open issue. If applicable, link:

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that causes existing functionality to not work as expected)
• Change requires a documentation update

What is the destination branch of this PR?

• Main
• Other. Specify:

How has this been tested?

Tests performed according to testing guidelines:

Checklist:

• My code follows the style guidelines of this project.
• [ x I have performed a self-review on my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• [ x 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.

[annacv]

🌮