⬆️ Bump anaconda from 2025.12 to 2026.06 (#562)

Bumps anaconda from 2025.12 to 2026.06.

---
updated-dependencies:
- dependency-name: anaconda
  dependency-version: '2026.06'
  dependency-type: direct:production
...

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Author: dependabot[bot]

environment.yml

@@ -3,7 +3,7 @@ channels:
   - default
 dependencies:
   - python=3.13
-  - anaconda=2025.12
+  - anaconda=2026.06
   - pip
   - pip:
     - jupyter-book>=1.0.4post1,<2.0