Mount /etc/hosts into container (#100475)
Follow up after https://github.com/pytorch/pytorch/pull/100436 to disable download.pytorch.org access over ipv6 access problems.
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### <samp>🤖 Generated by Copilot at 55c9443</samp>
This pull request improves the network configuration of the test-pytorch-binary GitHub action and workflow by mounting the host's `/etc/hosts` file into the container. This enables the container to resolve hostname aliases consistently with the host machine.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/100475
Approved by: https://github.com/huydhn
