feat: avoid expired thumbnails

[jemayn]

In combination with limbo-works/Limbo.Integrations.Skyfish#3 this PR will generate new img thumbnail urls each time they are called.

[abjerner]

@jemayn I can confirm that this builds with the newest version of the integration package 👍

Btw - ideally you shouldn't bump the value of the <Version> for feature changes. Eg. if we're later to revert or cherry pick commits, I prefer that the version is bumped in a separate commit (typically the one where we'd also build the NuGet package).