Use `range` instead of `LinRange`

[JeffFessler]

More concise. Requires Julia 1.7 because positional arguments for range first appeared then.

[codecov[bot]]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage :thumbsup:

Coverage data is based on head (87c3744) compared to base (ae3d370). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #69 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 20 20 Lines 592 592 ========================================= Hits 592 592 ``` | [Impacted Files](https://codecov.io/gh/JuliaImageRecon/ImagePhantoms.jl/pull/69?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [src/shepplogan.jl](https://codecov.io/gh/JuliaImageRecon/ImagePhantoms.jl/pull/69/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL3NoZXBwbG9nYW4uamw=) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None)

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