sphinx: Bump urllib3 version

While not a direct issue for us, urllib3 before 1.26.17 is vulnerable to
CVE-2023-43804 to bump our version up.

Reported-by: GitHub dependabot
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

Use urllib3 2.0.6
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/doc/sphinx/requirements.txt b/doc/sphinx/requirements.txt
index 6ccbe52..6d45a3f 100644
--- a/doc/sphinx/requirements.txt
+++ b/doc/sphinx/requirements.txt
@@ -23,4 +23,4 @@
 sphinxcontrib-jsmath==1.0.1
 sphinxcontrib-qthelp==1.0.3
 sphinxcontrib-serializinghtml==1.1.5
-urllib3==1.26.9
+urllib3==2.0.6