Fix loki

[normanrz]

Loki expects all key-value pairs to have string values. It seems like older versions (2.7) didn't validate that strictly, though. The new versions (2.9) do. This PR sprinkles in a few toString calls.

Steps to test:

• Enable voxelytics in config, set a loki uri
• Run a vx workflow against your local webknossos

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• Updated changelog

[fm3]

LGTM.

I guess we could also just replace the .as[Long] by .as[String] in these spots, but no strong opinion.

[normanrz]

I guess we could also just replace the .as[Long] by .as[String] in these spots, but no strong opinion.

I think that would expect a string in the json, but these are numbers.

[fm3]

I think that would expect a string in the json, but these are numbers.

Yeah that may be right. Feel free to merge as is then :)