Bump urllib3 from 1.25.3 to 1.26.5

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.25.3 to 1.26.5.
- [Release notes](https://github.com/urllib3/urllib3/releases)
- [Changelog](https://github.com/urllib3/urllib3/blob/main/CHANGES.rst)
- [Commits](urllib3/urllib3@1.25.3...1.26.5)

---
updated-dependencies:
- dependency-name: urllib3
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements.txt

@@ -29,7 +29,7 @@ smart-open==1.8.4
 tensorflow==2.3.0
 termcolor==1.1.0
 tqdm==4.41.1
-urllib3==1.25.3
+urllib3==1.26.5
 boto3==1.10.50
 botocore==1.13.50
 pymc3==3.11.0