add jonasz-lasut as maintainer

[erhancagirici]

Description of your changes

Adds Jonasz Łasut-Balcerzak (jonasz-lasut) as a maintainer of provider-upjet-aws per the Crossplane governance process.

• adds OWNERS.md entry
• adds @jonasz-lasut to CODEOWNERS as a fallback reviewer

I have:

• Read and followed Crossplane's contribution process.
• Run make generate and committed the results (ideally in a separate commit). N/A — no generated files affected.
• Not made any manual changes to generated files, and verified this with make check-diff. N/A — no generated files affected.

How has this code been tested

N/A

• Visual review of the OWNERS.md and CODEOWNERS diff.
• Approval per the 2/3 super-majority requirement of existing maintainers in GOVERNANCE.md.

[ulucinar]

Thank you @erhancagirici.