"copy_content_to_output_dir: preserve_newest" breaks paket.lock

Description

When I put "copy_content_to_output_dir: preserve_newest" into my paket.dependencies file, an incorrect paket.lock is generated. paket.lock is incorrectly generated with "COPY-CONTENT-TO-OUTPUT-DIR: PRESERVE-NEWEST". I can no longer run ".paket/paket install" or build any projects until I update paket.lock to have "PRESERVE_NEWEST"

Note that the difference is a dash versus an underscore.

My team believes the bug is here:
https://github.com/fsprojects/Paket/blob/b2feccc8f9e49f731083d2e2bfc5f47e5328eaa8/src/Paket.Core/PaketConfigFiles/LockFile.fs#L71

Repro steps

Please provide the steps required to reproduce the problem

1. Add "copy_content_to_output_dir: preserve_newest" near the beginning of your paket.dependencies file
2. Run ".paket/paket install"
3. Re-run ".paket/paket install". Observe that it fails
4. Try to build any of the .csproj files in your solution. Observe that : The command ""....paket\paket.exe" restore --references-file "..."" exited with code 1. (Edited to remove personal information)

Expected behavior

• paket.lock should have "COPY-CONTENT-TO-OUTPUT-DIR: PRESERVE_NEWEST"
• You should be able to re-run ".paket/paket install"
• You should be able to build your solution

Actual behavior

Re-running ".paket/paket install" fails with:

`Paket version 5.257.0
Performance:

• Runtime: 491 milliseconds
  Paket failed with
  -> Error during parsing of '...\opti\paket.lock'.
  -> Unknown copy_content_to_output_dir settings: "preserve-newest"
  `

Projects in my solution fail with:
1> Paket failed with 1> -> Error during parsing of '...\paket.lock'. 1> -> Unknown copy_content_to_output_dir settings: "preserve-newest"

Known workarounds

Manually edit paket.lock to have "COPY-CONTENT-TO-OUTPUT-DIR: PRESERVE_NEWEST"

Start in src/Paket.Core/PaketConfigFiles/LockFile.fs at the referenced line, then reproduce the issue using paket.dependencies and .paket/paket install. Compare the generated paket.lock value with the expected PRESERVE_NEWEST spelling and verify that install and the affected project builds succeed afterward.