Update openapi-generator-cli.sh (#2065)

* `jq` executable is a much cleaner way to get version number
* Using `jq` and getting `releases` instead of `tags` allows us to get latest stable release

bin/utils/openapi-generator-cli.sh

@@ -20,7 +20,7 @@
 ####
 set -o pipefail
 
-for cmd in {mvn,python,curl}; do
+for cmd in {mvn,jq,curl}; do
   if ! command -v ${cmd} > /dev/null; then
   >&2 echo "This script requires '${cmd}' to be installed."
     exit 1
@@ -28,8 +28,8 @@ for cmd in {mvn,python,curl}; do
 done
 
 function latest.tag {
-  local uri="https://api.github.com/repos/${1}/tags"
-  curl -s ${uri} | python -c "import sys, json; print json.load(sys.stdin)[0]['name'][1:]"
+  local uri="https://api.github.com/repos/${1}/releases"
+  curl -s ${uri} | jq -r 'first(.[]|select(.prerelease==false)).tag_name
 }
 
 ghrepo=openapitools/openapi-generator
@@ -57,4 +57,4 @@ java -ea                          \
   -Xms512M                        \
   -Xmx1024M                       \
   -server                         \
-  -jar ${DIR}/${jar} "$@"
+  -jar ${DIR}/${jar} "$@"