Plugin doesn't work with APIs that require "query param buckets is not a number"

[rekjuh]

Describe the bug
When connecting to certain APIs, the plugin doesn't work (= cannot make isochrone polygons). When testing the API with another program (e.g. Insomnia) and adding the parameters that Catchment plugin sends, API gives the following error:

{
"message": "query param buckets is not a number.",
"hints": [
{
"message": "query param buckets is not a number.",
"details": "java.lang.IllegalArgumentException"
}
]
}

To Reproduce
Steps to reproduce the behavior:

1. Create a few points on a new QGIS layer
2. Open the Catchment plugin and select the layer that you just created
3. Use the following API: https://graphhopper.lund.se/
4. Try to calculate isochrones
5. Get error "No results" etc.

Expected behavior
What Catcment should do is to send a number value for buckets.

Screenshots

The API works when buckets has been changed to a number.

Desktop (please complete the following information):

• Plugin: 0.4.3.
• QGIS 3.28.6
• Python: 3.8
• OS: Windows 10

Additional context
None