Fix run with docker instructions

Author: pradtke

README.md

@@ -89,17 +89,16 @@ of the `casserver` module mounted in the container, along with some configuratio
 "live" in the container, allowing you to test and iterate different things.
 
 ```bash
-# Note: this currently errors on this module requiring a newer version of `simplesamlphp/xml-common` than what is in the base image
 docker run --name ssp-casserver-dev \
    --mount type=bind,source="$(pwd)",target=/var/simplesamlphp/staging-modules/casserver,readonly \
   -e STAGINGCOMPOSERREPOS=casserver \
-  -e COMPOSER_REQUIRE="simplesamlphp/simplesamlphp-module-casserver:@dev simplesamlphp/simplesamlphp-module-preprodwarning"
+  -e COMPOSER_REQUIRE="simplesamlphp/simplesamlphp-module-casserver:@dev simplesamlphp/simplesamlphp-module-preprodwarning" \
   -e SSP_ADMIN_PASSWORD=secret1 \
   --mount type=bind,source="$(pwd)/docker/ssp/module_casserver.php",target=/var/simplesamlphp/config/module_casserver.php,readonly \
   --mount type=bind,source="$(pwd)/docker/ssp/authsources.php",target=/var/simplesamlphp/config/authsources.php,readonly \
   --mount type=bind,source="$(pwd)/docker/ssp/config-override.php",target=/var/simplesamlphp/config/config-override.php,readonly \
   --mount type=bind,source="$(pwd)/docker/apache-override.cf",target=/etc/apache2/sites-enabled/ssp-override.cf,readonly \
-   -p 443:443 cirrusid/simplesamlphp:v2.3.2
+   -p 443:443 cirrusid/simplesamlphp:v2.3.5
 ```
 
 Visit [https://localhost/simplesaml/](https://localhost/simplesaml/) and confirm you get the default page.