fix(dap): dynamic library path setup fix

[morfnasilu]

The PR fixes two small issues in the add_dynamic_library_paths method:

1. Dynamic linking didn't work on macOS due to a typo in the DYLD_LIBRARY_PATH constant.
2. Dynamic linking didn't work while using nightly toolchain (at least on macOS).

The problem was found when I tried to use rustaceanvim with Cargo.toml settings recommended for bevy engine: (https://bevyengine.org/learn/quick-start/getting-started/setup/).

FYI: Unfortunately I can't test that on systems.

[github-actions]

Review Checklist

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If applicable:

• Tested
  • Tests have been added.
  • Tested manually (Steps to reproduce in PR description).
• Updated documentation.
• Updated CHANGELOG.md

[mrcjkb]

LGTM

Thanks 🙏

[mrcjkb]

I'll prepare a release later today 😃