Version hash should include the image from launchPlan.workflow.nodes

[pingsutw]

Why are the changes needed?

The version won’t change if you update the requirements.txt file in the imageSpec and run a launch plan with Pyflyte.

from union import workflow, task, LaunchPlan, ImageSpec

custom_image = ImageSpec(
    name="runlp",
    requirements="requirements.txt",
    registry="pingsutw",
    builder="default",
    pip_extra_args="--prerelease=allow",
)


@task(container_image=custom_image)
def something(region: str, start_date: str) -> str:
    return f"{start_date}-{region}"


@workflow
def wf(region: str = "eu", start_date: str = "2024-01") -> str:
    return something(region=region, start_date=start_date)


qa_lp = LaunchPlan.get_or_create(
    name="qa_lp",
    workflow=wf,
)

What changes were proposed in this pull request?

This pull request updates the _get_image_names method in flytekit/remote/remote.py to handle LaunchPlan entities. The most important change is the addition of logic to extract image names from the nodes of a LaunchPlan's associated workflow.

Key Changes:

Enhancement to _get_image_names method:

• Added a condition to check if the entity is a LaunchPlan. If true, the method now iterates over the nodes in the LaunchPlan's workflow to collect image names, ensuring proper handling of this entity type. ([flytekit/remote/remote.pyR1341-R1345](https://github.com/flyteorg/flytekit/pull/3290/files#diff-c56afc489e5060224889036253b85ae7c7f1df9f0f7b1130916d9c614293cbb9R1341-R1345))## Tracking issue

Summary by Bito

This pull request enhances the `_get_image_names` method in `flytekit/remote/remote.py` by adding logic to handle `LaunchPlan` entities, enabling the correct extraction of image names from associated workflow nodes. This addresses a limitation in the previous implementation.