chore(deps): bump custom/plugins/zsh-history-substring-search

Bumps [custom/plugins/zsh-history-substring-search](https://github.com/zsh-users/zsh-history-substring-search) from `8dd05bf` to `87ce96b`.
- [Release notes](https://github.com/zsh-users/zsh-history-substring-search/releases)
- [Commits](zsh-users/zsh-history-substring-search@8dd05bf...87ce96b)

---
updated-dependencies:
- dependency-name: custom/plugins/zsh-history-substring-search
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>