[11.x] Support spatie/pdf-to-image v3

[Jubeki]

With the release of spatie/pdf-to-image v3, the spatie media library is no longer compatible with the current implementation.

This PR makes a breaking change by needing v3 instead of v2 and using the corresponding new methods.

[freekmurze]

I think creating a new major simply for updating the dependency might be a much.

Could you allow for both v2 and v3 to be installed? In code, we should check which version is installed (you can do that with the InstalledVersions class from Composer, and then call the right methods for that version.

This way we can support v3 without making breaking changes.

[Jubeki]

@freekmurze yeah, will do that!

[Jubeki]

@freekmurze Do you want a new test workflow for testing v2 and v3 or do you want it with a matrix like I is now?

[freekmurze]

Like now is fine. Prefer-lowest will pull in v2, prefer-stable v3. That's good enough for me!

[freekmurze]

Thank you!