Use fstrings

[MichaelHinrichs]

Make sure your submission meets the following requirements (summarized from the mod guidelines):

• Follow the schema. An automated check will validate this PR against the schema.
• Indent using four spaces. An automated check will validate this PR indents properly.
• Your NeosMod.Version should match the version in the manifest.
• You should not monopack libraries into your mod DLL.
• Do not remove old versions.
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• In order to reduce merge conflicts avoid adding mods at the very end of the file.

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I'm not submitting a new mod, so some of the checkboxes are N/A. The rest of the requirements are technically followed, by not doing anything to manifest.json.