Don't override custom provider on update

[SlowMo24]

Here's what I did

I updated the plugin through qgis.

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Here's what I got

my custom providers are gone.

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Here's what I was expecting

my custom providers to be preserved

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Here's what I think could be improved

store custom providers in a different place or in a file that does not get overwritten.

[SlowMo24]

also the api-key for the central api is lost each time

[nilsnolde]

good point. it's the same file, config.yml. you got time for a PR? :wink: