[Bug] importing gpx from Strava fails

[AntoineChalons]

Describe the bug
I go to strava, export my activity to GPX, try to import in polyrun and get "internal server error"

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
A clear and concise description of what you expected to happen.

Screenshots

Smartphone (please complete the following information):

• Device: Laptop computer
• OS: Windows 10 + Firefox 96.0.1
• Polyrun version 0.12.0

Additional context
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