Tools/setup/ubuntu.sh: fix for Ubuntu 20.04 - use gazebo11

Tools/setup/ubuntu.sh

@@ -176,10 +176,13 @@ if [[ $INSTALL_SIM == "true" ]]; then
 
 	if [[ "${UBUNTU_RELEASE}" == "18.04" ]]; then
 		java_version=11
+		gazebo_version=9
 	elif [[ "${UBUNTU_RELEASE}" == "20.04" ]]; then
 		java_version=14
+		gazebo_version=11
 	else
 		java_version=14
+		gazebo_version=11
 	fi
 	# Java (jmavsim or fastrtps)
 	sudo DEBIAN_FRONTEND=noninteractive apt-get -y --quiet --no-install-recommends install \
@@ -197,14 +200,14 @@ if [[ $INSTALL_SIM == "true" ]]; then
 	wget http://packages.osrfoundation.org/gazebo.key -O - | sudo apt-key add -
 	sudo DEBIAN_FRONTEND=noninteractive apt-get -y --quiet --no-install-recommends install \
 		dmidecode \
-		gazebo9 \
+		gazebo$gazebo_version \
 		gstreamer1.0-plugins-bad \
 		gstreamer1.0-plugins-base \
 		gstreamer1.0-plugins-good \
 		gstreamer1.0-plugins-ugly \
 		gstreamer1.0-libav \
 		libeigen3-dev \
-		libgazebo9-dev \
+		libgazebo$gazebo_version-dev \
 		libgstreamer-plugins-base1.0-dev \
 		libimage-exiftool-perl \
 		libopencv-dev \