chore(deps): Bump jupyter-server from 2.19.0 to 2.20.0 in /tests

Bumps [jupyter-server](https://github.com/jupyter-server/jupyter_server) from 2.19.0 to 2.20.0.
- [Release notes](https://github.com/jupyter-server/jupyter_server/releases)
- [Changelog](https://github.com/jupyter-server/jupyter_server/blob/main/CHANGELOG.md)
- [Commits](jupyter-server/jupyter_server@v2.19.0...v2.20.0)

---
updated-dependencies:
- dependency-name: jupyter-server
  dependency-version: 2.20.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

tests/requirements.colab.2024.02.txt

@@ -11,7 +11,7 @@ Cython==3.2.5
 graphviz==0.21
 jupyter-client==8.8.0
 jupyter-console==6.6.3
-jupyter-server==2.19.0
+jupyter-server==2.20.0
 jupyter_core==5.9.1
 jupyterlab_pygments==0.3.0
 jupyterlab_widgets==3.0.16

tests/requirements.colab.2025.02.txt

@@ -13,7 +13,7 @@ html5lib==1.1
 ipywidgets==8.1.8
 jupyter-client==8.8.0
 jupyter-console==6.6.3
-jupyter-server==2.19.0
+jupyter-server==2.20.0
 jupyter_core==5.9.1
 jupyterlab_pygments==0.3.0
 jupyterlab_widgets==3.0.16

tests/requirements.colab.2026.02.txt

@@ -13,7 +13,7 @@ html5lib==1.1
 ipywidgets==8.1.8
 jupyter-client==8.8.0
 jupyter-console==6.6.3
-jupyter-server==2.19.0
+jupyter-server==2.20.0
 jupyter_core==5.9.1
 jupyterlab_pygments==0.3.0
 jupyterlab_widgets==3.0.16