Problem:    Vim9: error for not using string doesn't mention argument.
Solution:   Add argument number.
https://github.com/vim/vim/commit/f28f2ac425600b88da0bdcc12a82cd620f575681

dispatch.sr.ht is being deprecated, meaning that using sourcehut CI
won't be possible (see https://github.com/neovim/neovim/issues/19609).
Since Github Actions doesn't provide any BSD runners an external service
is required and Cirrus CI seems like a good replacement for sourcehut.

Initially experimented with using FreeBSD and OpenBSD virtual machines
in GitHub Actions, but Cirrus has been a much better fit with better
performance, logs and overall experience.

Failing tests are automatically skipped on FreeBSD regardless if it's on
CI or not. Ideally these tests should only be skipped in CI with the
help of `isCI` helper function. Unfortunately, the tests don't recognize
the environment variable CIRRUS_CI even if it's set manually. This
workaround is good enough for the time being, but we might want to only
skip tests when using the CI (or even better, fix the failing tests).

Closes: https://github.com/neovim/neovim/issues/19609

Co-authored-by: Mathias Fussenegger <f.mathias@zignar.net>

Problem:    #{g:x} was seen as a curly-braces expression.
Solution:   Do never see #{} as a curly-braces expression. (closes vim/vim#11075)
https://github.com/vim/vim/commit/7c7e1e9b98d4e5dbe7358c795a635c6f1f36f418

Also add missing fcs, lcs and winhighlight to list of key-value options for `vim.opt`.

Co-authored-by: ii14 <ii14@users.noreply.github.com>

feat(treesitter): use weak tables when possible

Also add the defaulttable function to create a table whose values are created when a key is missing.

Doing so on `BufDelete` has issues:
  - `BufDelete` is also fired for listed buffers that are made unlisted.
  - `BufDelete` is not fired for unlisted buffers that are deleted.

This means that diagnostics will be lost for a buffer that becomes unlisted.

It also means that if an entry exists for an unlisted buffer, deleting that
buffer later will not remove its entry from the cache (and you may see "Invalid
buffer id" errors when using diagnostic functions if it was wiped).

Instead, remove a buffer from the cache if it is wiped out.
This means simply `:bd`ing a buffer will not clear its diagnostics now.

build(deps): bump libvterm to 0.3-RC1