TAG ENV, update alessandro's and Kristina's roles

[leonardpahlke]

• Krisitna Devochko onboarding issue: https://github.com/cncf/tag-env-sustainability/issues/563
• Alessandro Vozza onboarding issue: https://github.com/cncf/tag-env-sustainability/issues/564

[clowarden[bot]]

Validation succeeded

✅ The proposed configuration changes are valid!

Configuration changes

Directory

• ams0 is now a member of team tag-env-sustainability
• guidemetothemoon is now a member of team tag-env-chairs

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🔸 Please review the changes detected as they will be applied immediately once this PR is merged 🔸

[leonardpahlke]

cc @RobertKielty