The GChat cURL command has a stray quote mark as well as backticks that cause the version number to be interpreted as a command:

curl -X POST "${WEBHOOK_URL}" -H 'Content-Type: application/json' -d "{ "text": "${ANNOUNCING_ID}" ${VERSION} is available now" }" || true

We should remove the stray tick and update the command so that the backticks are added outside of the JSON expression.