Move to elixir 1.16 for develop flake, nix 23.11.

[crertel]

Updates to Elixir 1.16, nix 23.11 in the development flake. This is done to catch a compiler error introduced in the recent spurt of merges.

Description

Updates to Elixir 1.16, nix 23.11 in the development flake. This is done to catch a compiler error introduced in the recent spurt of merges.

Motivation and Context

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• Improvement/refactoring (non-breaking change that doesn't add any feature
  but make things better)

Checklist

• Check other PRs and make sure that the changes are not done yet.