fix dockerfile

[0xSulpiride]

Description

• it looks like the latest release of python3 somehow broke the dockerfile, installing py3-setuptools fixed it (like here chore: fix broken docker ChainSafe/lodestar#6813)

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Other (please describe):

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