use json api url + report curl/wget error on fail

Signed-off-by: shoce <yogze@icloud.com>

scripts/get-helm-3

@@ -108,11 +108,17 @@ verifySupported() {
 checkDesiredVersion() {
   if [ "x$DESIRED_VERSION" == "x" ]; then
     # Get tag from release URL
-    local latest_release_url="https://github.com/helm/helm/releases"
+    local latest_release_url="https://api.github.com/repos/helm/helm/releases/latest"
+    local latest_release_response=""
     if [ "${HAS_CURL}" == "true" ]; then
-      TAG=$(curl -Ls $latest_release_url | grep 'href="/helm/helm/releases/tag/v3.[0-9]*.[0-9]*\"' | sed -E 's/.*\/helm\/helm\/releases\/tag\/(v[0-9\.]+)".*/\1/g' | head -1)
+      latest_release_response=$( curl -L --silent --show-error --fail "$latest_release_url" 2>&1 || true )
     elif [ "${HAS_WGET}" == "true" ]; then
-      TAG=$(wget $latest_release_url -O - 2>&1 | grep 'href="/helm/helm/releases/tag/v3.[0-9]*.[0-9]*\"' | sed -E 's/.*\/helm\/helm\/releases\/tag\/(v[0-9\.]+)".*/\1/g' | head -1)
+      latest_release_response=$( wget "$latest_release_url" -O - 2>&1 || true )
+    fi
+    TAG=$( echo "$latest_release_response" | grep '"tag_name"' | sed -E 's/.*"(v[0-9\.]+)".*/\1/g' )
+    if [ "x$TAG" == "x" ]; then
+      printf "Could not retrieve the latest release tag information from %s: %s\n" "${latest_release_url}" "${latest_release_response}"
+      exit 1
     fi
   else
     TAG=$DESIRED_VERSION