Update ubuntu.sh with Linux Mint 21.3 version

Tools/setup/ubuntu.sh

@@ -66,6 +66,8 @@ elif [[ "${UBUNTU_RELEASE}" == "20.04" ]]; then
 	echo "Ubuntu 20.04"
 elif [[ "${UBUNTU_RELEASE}" == "22.04" ]]; then
 	echo "Ubuntu 22.04"
+elif [[ "${UBUNTU_RELEASE}" == "21.3" ]]; then
+	echo "Linux Mint 21.3"
 fi
 
 
@@ -146,7 +148,7 @@ if [[ $INSTALL_NUTTX == "true" ]]; then
 		util-linux \
 		vim-common \
 		;
-	if [[ "${UBUNTU_RELEASE}" == "20.04" || "${UBUNTU_RELEASE}" == "22.04" ]]; then
+	if [[ "${UBUNTU_RELEASE}" == "20.04" || "${UBUNTU_RELEASE}" == "22.04" || "${UBUNTU_RELEASE}" == "21.3" ]]; then
 		sudo DEBIAN_FRONTEND=noninteractive apt-get -y --quiet --no-install-recommends install \
 		kconfig-frontends \
 		;
@@ -205,6 +207,8 @@ if [[ $INSTALL_SIM == "true" ]]; then
 		java_version=13
 	elif [[ "${UBUNTU_RELEASE}" == "22.04" ]]; then
 		java_version=11
+	elif [[ "${UBUNTU_RELEASE}" == "21.3" ]]; then
+		java_version=11
 	else
 		java_version=14
 	fi
@@ -228,6 +232,17 @@ if [[ $INSTALL_SIM == "true" ]]; then
 		echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/pkgs-osrf-archive-keyring.gpg] http://packages.osrfoundation.org/gazebo/ubuntu-stable $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/gazebo-stable.list > /dev/null
 		sudo apt-get update -y --quiet
 
+		# Install Gazebo
+		gazebo_packages="gz-garden"
+	elif [[ "${UBUNTU_RELEASE}" == "21.3" ]]; then
+		echo "Gazebo (Garden) will be installed"
+		echo "Earlier versions will be removed"
+		# Add Gazebo binary repository
+		sudo wget https://packages.osrfoundation.org/gazebo.gpg -O /usr/share/keyrings/pkgs-osrf-archive-keyring.gpg
+		echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/pkgs-osrf-archive-keyring.gpg] http://packages.osrfoundation.org/gazebo/ubuntu-stable jammy main" | sudo tee /etc/apt/sources.list.d/gazebo-stable.list > /dev/null
+
+		sudo apt-get update -y --quiet
+
 		# Install Gazebo
 		gazebo_packages="gz-garden"
 	else