Correcting `heart-uci/docker.sh`

examples/heart-uci/docker.sh

 #!/bin/bash
 cd examples/heart-uci
 # Write server script and run server container
-cat <<- EOF >> docker_server.sh
+cat <<- EOF > docker_server.sh
 	python gen_ssl.py
 	python server.py 4
 	EOF
-docker run -dt --network="host" --mount type=bind,source=$PWD,target=/experiment --name server --env script=./docker_server.sh declearn
+docker run -dt --network="host" --mount type=bind,source=$PWD,target=/experiment --name server --env script=./docker_server.sh registry.gitlab.inria.fr/magnet/declearn/declearn2:declearn-base
+# Ensure server is done generating certificates
+sleep 2
 # Run client scripts and run containers
 for CLIENT in cleveland hungarian switzerland va
 do
-	cat <<- EOF >> docker_$CLIENT.sh
-    		python client.py $CLIENT
+	cat <<- EOF > docker_$CLIENT.sh
+    	python client.py $CLIENT
 		EOF
-    	docker run -dt --network=container:server --mount type=bind,source=$PWD,target=/experiment --name $CLIENT --env script=./docker_$CLIENT.sh declearn
+    	docker run -dt --network=container:server --mount type=bind,source=$PWD,target=/experiment --name $CLIENT --env script=./docker_$CLIENT.sh registry.gitlab.inria.fr/magnet/declearn/declearn2:declearn-base
 done