build(deps): update jishaku requirement from ~=2.5.2 to ~=2.6.0

Updates the requirements on [jishaku](https://github.com/scarletcafe/jishaku) to permit the latest version.
- [Release notes](https://github.com/scarletcafe/jishaku/releases)
- [Changelog](https://github.com/scarletcafe/jishaku/blob/master/docs/whatsnew.rst)
- [Commits](scarletcafe/jishaku@2.5.2...2.6.0)

---
updated-dependencies:
- dependency-name: jishaku
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -1,7 +1,7 @@
 discord.py~=2.4.0
 feedparser~=6.0.11
 gspread~=6.1.4
-jishaku~=2.5.2
+jishaku~=2.6.0
 markdownify~=0.13.1
 psutil~=6.1.0
 pytz~=2024.2