fix: update Finch on Windows rootfs update workflow

[austinvazquez]

Issue #, if available:
In #326, it was found the update rootfs workflow was not working due to the filename pattern still searching for .zst archives. The pattern was updated to .gz to match the release archives in S3; however, the regular expression does not work with grep's basic regular expression engine.

Description of changes:
This change updates the find in S3 utility function to use grep's extended regular expression engine and updates the filename patterns.

Testing done:
Tested using local aws S3 queries:

Rootfs bundle:

macedonv@localhost:~$ aws s3 ls s3://***/common/x86-64 --recursive | grep -E 'finch-rootfs-production-amd64-[0-9]+\.tar\.gz$' | tail -n 1 | sort | awk '{print $4}'
common/x86-64/finch-rootfs-production-amd64-1715724303.tar.gz
macedonv@localhost:~$ 

Lima bundle:

macedonv@localhost:~$ aws s3 ls s3://***/aarch64 --recursive | grep -E 'lima-and-qemu.macos-aarch64\.[0-9]+\.tar\.gz$' | tail -n 1 | sort | awk '{print $4}'
aarch64/lima-and-qemu.macos-aarch64.1719307443.tar.gz
macedonv@localhost:~$ 

• I've reviewed the guidance in CONTRIBUTING.md

License Acceptance

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.