Fix warnings in lnxtools.sh

change apt to apt-get

lnxtools.sh

@@ -5,13 +5,13 @@ DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
 if [ "$1" == "prepare" ]
 then
     echo "Preparing your system for the first run"
-    apt update -y && apt upgrade -y
-    apt install python3.7 python3-pip -y
+    apt-get update -y && apt-get upgrade -y
+    apt-get install python3.7 python3-pip -y
     pip3 install setuptools wheel regex
-    cd $DIR
+    cd "$DIR" || exit
     pip3 install -r requirements.txt
     python3 main.py helloworld
 else
-    cd $DIR
+    cd "$DIR" || exit
     python3 main.py "$@"
 fi