Use POSIX compatible way to detect Helm binary

Author: Michael Sauter

install-binary.sh

@@ -16,7 +16,7 @@ if type cygpath >/dev/null 2>&1; then
   HELM_PLUGIN_DIR="$(cygpath -u "${HELM_PLUGIN_DIR}")"
 fi
 
-[ -z "$HELM_BIN" ] && HELM_BIN=$(which helm)
+[ -z "$HELM_BIN" ] && HELM_BIN=$(command -v helm)
 HELM_MAJOR_VERSION=$("${HELM_BIN}" version --client --short | awk -F '.' '{print $1}')
 
 HELM_HOME=$("${HELM_BIN}" home --debug=false)