Fixed shellcheck issue with using which

Signed-off-by: Andreas Maier <maiera@de.ibm.com>

os_setup.sh

@@ -13,7 +13,7 @@ elif [[ "$(uname -s)" == "Linux" ]]; then
   if [[ -f /etc/os-release ]]; then
     source /etc/os-release
     distro_id=$ID
-  elif [[ -n $(which lsb_release) ]]; then
+  elif [[ -n $(command -v lsb_release) ]]; then
     distro_id=$(lsb_release -i -s)
   else
     echo "Error: Cannot determine Linux distro."
@@ -34,13 +34,13 @@ fi
 
 echo "Installing OS-level prerequisite packages for ${platform}..."
 
-if [[ -n $(which yum 2>/dev/null) ]]; then
+if [[ -n $(command -v yum 2>/dev/null) ]]; then
   sudo yum makecache fast
   sudo yum -y install libffi-devel
-elif [[ -n $(which apt-get 2>/dev/null) ]]; then
+elif [[ -n $(command -v apt-get 2>/dev/null) ]]; then
   sudo apt-get --quiet update
   sudo apt-get --yes install libffi-dev
-elif [[ -n $(which choco 2>/dev/null) ]]; then
+elif [[ -n $(command -v choco 2>/dev/null) ]]; then
   echo "Nothing to install for platform $platform"
 else
   echo "Warning: Unsupported installer (Platform: $platform)"