ci: use SUMO 1.21.0 for testing

Jenkinsfile

@@ -8,7 +8,7 @@ kind: Pod
 spec:
   containers:
   - name: maven-sumo
-    image: eclipsemosaic/mosaic-ci:jdk17-sumo-1.20.0
+    image: eclipsemosaic/mosaic-ci:jdk17-sumo-1.21.0
     command:
     - cat
     tty: true

README.md

@@ -50,7 +50,7 @@ Additional simulators and assessment features are provided by [Fraunhofer FOKUS]
 
 ## Related Repositories
 
-* [Eclipse SUMO](https://github.com/eclipse/sumo) is coupled directly using the TraCI interface. We recommend using the SUMO release `1.20.0`.
+* [Eclipse SUMO](https://github.com/eclipse/sumo) is coupled directly using the TraCI interface. We recommend using the SUMO release `1.21.0`.
 * The coupling to [ns-3](https://www.nsnam.org) is realized by a federate implementation which can be found [in our MOSAIC Addons repository](https://github.com/mosaic-addons/ns3-federate). 
   We currently support ns-3 version `3.36.1`. 
 * The coupling to [OMNeT++](https://omnetpp.org) is implemented in a very similar manner. The corresponding federate implementation can be found [in our MOSAIC Addons repository](https://github.com/mosaic-addons/omnetpp-federate). 
@@ -73,7 +73,7 @@ For a successful build you need the following software to be installed:
 
 * **Maven 3.1.x** or higher.
 * **Java 17**, or 21 - We recommend using the [Adoptium OpenJDK (aka Eclipse Temurin)](https://adoptium.net/?variant=openjdk17).
-* **SUMO 1.20.0** - Older versions > 1.2.0 are most probably supported, but not tested. The environment variable `SUMO_HOME` should be configured properly.
+* **SUMO 1.21.0** - Older versions > 1.2.0 are most probably supported, but not tested. The environment variable `SUMO_HOME` should be configured properly.
 
 ## Build
 

test/ci/ci-image-mvn-sumo/Dockerfile

@@ -9,6 +9,6 @@ WORKDIR /home/jenkins
 RUN apt-get update &&  \
     apt-get install -y --allow-unauthenticated software-properties-common && \
     # adjust this output string to bypass potential caches
-    echo "Installing SUMO 1.20.0" && \
+    echo "Installing SUMO 1.21.0" && \
     add-apt-repository ppa:sumo/stable && \
     apt-get install -y sumo

test/ci/ci-image-mvn-sumo/README.md

@@ -10,9 +10,9 @@ build and tag the docker image with the latest SUMO version. This image should b
 and available in the PPA.
 
 ```shell script
-docker build . -t eclipsemosaic/mosaic-ci:jdk17-sumo-1.20.0
+docker build . -t eclipsemosaic/mosaic-ci:jdk17-sumo-1.21.0
 docker login
-docker push eclipsemosaic/mosaic-ci:jdk17-sumo-1.20.0
+docker push eclipsemosaic/mosaic-ci:jdk17-sumo-1.21.0
 ```  
 
 Afterwards, the image should be available here: https://hub.docker.com/r/eclipsemosaic/mosaic-ci/tags