Drop support for Node 18 and 23

[atwupack]

Several dependencies in the project have current versions that require at least Node 20.

• commander 14 requires Node 20
  • Commander 14 introduces option groups. These would be quite useful to separate dependency-check-cli arguments from the ones specific to our program.
• undici 7 requires Node 20.18.1
• walk-up-path 7 requires Node 20 or 22+
• Node 18 is EOL and should not used in productive environments anymore.
• @types/node needs to be upgraded to version 20.x

[atwupack]

After some testing it seems that commander 14 is still working fine with Node 18. The upgrade will happen with version 0.8.0.

[atwupack]

undici 7 officially supports only Node 24. For Node 20 version 6 should be used.
Currently we are using version 5 because some changes (e.g. the use of String.toWellFormed) is not working on Node 18.

[atwupack]

Node 23 is also EOL and isn't supported anymore.