chore: bump rules_oci from 1.8.0 to 2.0.0 in /oci_python_image

[ahans]

Docs over at rules_oci point here, but the current version is incompatible with the current version (oci_tarball was renamed). This PR updates the example.

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Changes are visible to end-users: yes

• Searched for relevant documentation and updated as needed: yes
• Breaking change (forces users to change their own code or config): no
• Suggested release notes appear below: no

Test plan

• Covered by existing test cases
• Manual testing; please provide instructions so we can reproduce:

bazel build //hello_world:image_load.tar

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Test

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[gregmagolan]

Thanks @ahans!