fix: Avoid unknown fields on config

[ajnavarro]

This will reduce headaches when adding wrong fields to the config.

Signed-off-by: Antonio Navarro Perez antnavper@gmail.com

[BigLep]

2022-12-01 standup conversation:

• Agreed on strict mode by default
• Provide environment variable to bypass validation
• We want to keep strict mode as possible for sharness
• We should have a test that validates that strict mode does raise an error when you use an invalid strict