Bump urllib3 from 1.26.18 to 1.26.19 in /.requirements (#1376)

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.26.18 to 1.26.19.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/1.26.19/CHANGES.rst)
- [Commits](urllib3/urllib3@1.26.18...1.26.19)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.requirements/docs.txt

@@ -90,6 +90,8 @@ pexpect==4.8.0
     # via ipython
 pickleshare==0.7.5
     # via ipython
+polars==0.20.31
+    # via -r docs.in
 prompt-toolkit==3.0.36
     # via ipython
 ptyprocess==0.7.0
@@ -137,7 +139,7 @@ traitlets==5.8.1
     #   matplotlib-inline
 unyt==2.9.3
     # via -r engineering.in
-urllib3==1.26.18
+urllib3==1.26.19
     # via requests
 watchdog==2.2.1
     # via mkdocs