Improve workflow security

[deckstose]

The recent supply chain attack on LiteLLM has shown that github workflows are very much able to be exploited. This PR tries to improve the situation by using a tool called zizmor to lint workflow files.

• Pin CI actions to hashes
  This directly tries to mitigate what happened in the recent attack where a uploaded release
  was replaced by deleting and recreating it. A pinned commit, which changed through the
  deletion, would have helped.
• Reduce permission scope

[github-advanced-security]

You are seeing this message because GitHub Code Scanning has recently been set up for this repository, or this pull request contains the workflow file for the Code Scanning tool.

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