Update core github actions to v4 (major)

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
actions/download-artifact	action	major	v3 -> v4
actions/upload-artifact	action	major	v3 -> v4

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Release Notes

actions/download-artifact (actions/download-artifact)

v4

Compare Source

actions/upload-artifact (actions/upload-artifact)

v4

Compare Source

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[roobre]

Breaking change seems to be that artifacts uploaded with v3 cannot be downloaded with v4. We should be fine with that as these artifacts are transitory.