bug: episode duration does not work properly in french

Describe the bug

episode duration does not work properly in french

Steps to reproduce

1. Configure your browser in french
2. go to an episode page (admin or public)
3. take a look at the episode duration

Expected behavior

Display duration in mn/sec

Actual behavior

Displays duration in sec only

Relevant logs and/or screenshots

https://podcast.podlibre.org/@fr/le-marche-du-podcast

Context

• Castopod: pipeline 183
• OS: Debian 10.5
• Browser: Firefox
• Web server: NGinx
• Cloud Panel

Possible fixes

Update the french format