feat: add 'exclude' input to filter versions

[Koan-Bot]

What

Add an exclude input that accepts a comma-separated list of versions to remove from the output.

Why

Users currently need shell-based post-processing (jq filters) to remove specific versions from the matrix. This is a common need — e.g., skipping a known-broken Perl version on a specific platform.

How

• perl_versions() accepts a new exclude string parameter
• Versions are parsed via decode_version(), so 5.32, v5.32, and devel all work
• Exclusion is applied before range filtering via a Set lookup
• 8 new test cases cover single/multiple exclusions, devel, v-prefix, empty input, and edge cases

Testing

• npm test — 71 tests pass (8 new for exclude)
• npm run build — dist rebuilt

[happy-barney]

• function should also silently accept serialized json array
  • user may use chain of perl-versions call passing result of one as argument of another
• consistency:
  • use function name parse_input_version_list
  • export it and call it same way as parse_input_version - before calling perl_versions

Follow-ups:

• target can be element of list, for example: list of versions included in target A but not included in target B
• include input parameter - when specified, versions are included into filtered list right before single-out is applied

[happy-barney]

Note 1:
Useless L65, that is already done by decode_version.
In fact, maybe we should also move L63 in it.

Note 2:
Please move exclusion into separated function, so this function will in future look like:

versions = perl_versions_target  (target);
versions = perl_versions_filter (versions, ...);
versions = perl_versions_exclude (versions, ...);
versions = perl_versions_include (versions, ...);
// hypothetical support for `asc`/`desc` ordering with `devel first` / `devel last` 
versions = perl_versions_sort (versions, ...);

return versions;