Computer worker upgrade feature

[ihsaan-ullah]

We need a feature in compute worker to communicate with codabench and check for any critical or non critical upgrades available

• If a critical upgrade is found, compute worker will fail with a nice message
• If the upgrade is not critical then computer worker prints a warning
• if no upgrade just execute normally

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Update

We decied to go for a minimum version that require no or less tweaks. This min version compares local image date with remote image date to figure out if local image is behind the remote. For more details check the PR #2377