Bump urllib3 from 1.25.7 to 1.26.5 in /transifex/requirements

Bumps [urllib3](https://github.com/urllib3/urllib3) from 1.25.7 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@1.25.7...1.26.5)

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

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

transifex/constraints.txt

@@ -1,2 +1,2 @@
 # transifex-client 0.12.4 did not pin urllib3, but requests cannot work with urllib3 1.25.2 (https://github.com/transifex/transifex-client/blob/128b212a5f07d1a1475ebd10fda0bf6dbbe2c055/requirements.txt)
-urllib3<1.25
+urllib3<1.27

transifex/requirements/edx-platform.txt

@@ -34,7 +34,7 @@ pyyaml==5.4               # via watchdog
 requests==2.22.0
 six==1.13.0               # via edx-opaque-keys, libsass, mock, paver, python-memcached, stevedore
 stevedore==1.31.0
-urllib3==1.25.7           # via requests
+urllib3==1.26.5           # via requests
 watchdog==0.9.0
 lxml==4.5.0