Bump urllib3 from 2.0.4 to 2.0.6 in /docs

Bumps [urllib3](https://github.com/urllib3/urllib3) from 2.0.4 to 2.0.6.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@2.0.4...2.0.6)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-type: indirect
...

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

docs/requirements.txt

@@ -20,8 +20,6 @@ idna==3.4
     # via requests
 imagesize==1.4.1
     # via sphinx
-importlib-metadata==6.8.0
-    # via sphinx
 jinja2==3.1.2
     # via sphinx
 markupsafe==2.1.3
@@ -30,8 +28,6 @@ packaging==23.1
     # via sphinx
 pygments==2.16.1
     # via sphinx
-pytz==2023.3
-    # via babel
 readthedocs-sphinx-search==0.1.1
     # via -r requirements.in
 requests==2.31.0
@@ -56,7 +52,5 @@ sphinxcontrib-qthelp==1.0.3
     # via sphinx
 sphinxcontrib-serializinghtml==1.1.5
     # via sphinx
-urllib3==2.0.4
+urllib3==2.0.6
     # via requests
-zipp==3.16.2
-    # via importlib-metadata