[Bug] App uses User-Agent containing 'okhttp' that is common in blocklists

[wouterfranken]

Describe the bug
The user-agent used by this app contains 'okhttp'. Such a User-Agent appears in a commonly used blocklist: https://github.com/JayBizzle/Crawler-Detect/blob/v1.3.5/raw/Crawlers.txt#L855. For example: OPNSense (open source firewall) blocks this user-agent by default in their nginx plugin (see https://github.com/opnsense/plugins/blob/25.7.2/www/nginx/src/opnsense/mvc/app/models/OPNsense/Nginx/Nginx.xml#L74) and also bunkerweb blocks this because it uses the before mentioned blocklist.

To Reproduce
Steps to reproduce the behavior:

1. Setup freshrss server behind nginx
2. Configure nginx to block user-agent that contains 'okhttp'
3. Try to connect with the freshrss server with readrops
4. Get a 403 error (or any other error code that is configured in nginx to respond when blocking)

Expected behavior
No error when using readrops.

This means you should not use the default okhttp User-Agent but set up a custom User-Agent to avoid being blocked.
The HomeAssistant android app had the same issue, they now use a custom User-Agent string: home-assistant/android#1364.

Environment information (please complete the following information):

• Account type: FreshRSS
• App version: 2.1.1
• Android version: Android 14
• Device type: OnePlus 9 Pro
• Store: F-Droid
• Stacktrace collected from crash screen

Additional context