Update Dockerfile

Trying to use Node:19 instead of Node:16 to fix error similar to: 
```
octokit/auth-app.js#465
```

Signed-off-by: Sean P. Goggins <s@goggins.com>

Dockerfile

@@ -1,7 +1,7 @@
-FROM node:16
+FROM node:19
 WORKDIR /app
 COPY package*.json ./
 RUN npm install
 COPY . .
 EXPOSE 2020
-CMD [ "npm", "start" ]
+CMD [ "npm", "start" ]