Prioritize version from pyproject.toml

[tofarr]

Prioritize version from pyproject.toml over importlib

• Include this change in the Release Notes. If checked, you must provide an end-user friendly description for your change below

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When running directly from poetry, I get the following:

>>> from openhands import get_version
>>> get_version()
'0.0.0.post2755+c5117bc48'

Which leads to...
docker.errors.NotFound: 404 Client Error for http+docker://localhost/v1.47/containers/openhands-runtime-vvLDWakILRMQYcw_AAAB/json: Not Found ("No such container: openhands-runtime-vvLDWakILRMQYcw_AAAB")

This PR prioritizes the version from the pyproject.toml so that runtime images can be built.

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To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:310ddce-nikolaik   --name openhands-app-310ddce   docker.all-hands.dev/all-hands-ai/openhands:310ddce