Fixes #15 Minor version number may contain non numbers (#16)

Co-authored-by: Andrei Kvapil <kvapss@gmail.com>

Author: va1ha11a

kubectl-node_shell

@@ -67,8 +67,8 @@ EOT
 )"
 
 # Support Kubectl <1.18
-m=$(kubectl version --client -o yaml | while read k v; do [ "$k" = minor: ] && echo "${v%\"*}"; done)
-if [ "${m#*\"}" -lt 18 ]; then
+m=$(kubectl version --client -o yaml | awk -F'[ :"]+' '$2 == "minor" {print $3+0}' )
+if [ "$m" -lt 18 ]; then
   generator="--generator=run-pod/v1"
 fi