chore(deps): bump regex from 2026.4.4 to 2026.5.9 in /hack/api-docs (#6330)

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

hack/api-docs/requirements.txt

@@ -31,7 +31,7 @@ pymdown-extensions==10.21.2
 python-dateutil==2.9.0.post0
 PyYAML==6.0.3
 pyyaml_env_tag==1.1
-regex==2026.4.4
+regex==2026.5.9
 requests==2.33.1
 six==1.17.0
 termcolor==3.3.0