view to getindex in schur_reduce

[codecov[bot]]

Codecov Report

Base: 97.15% // Head: 97.15% // No change to project coverage :thumbsup:

Coverage data is based on head (7930e51) compared to base (567650a). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #70 +/- ## ======================================= Coverage 97.15% 97.15% ======================================= Files 17 17 Lines 351 351 ======================================= Hits 341 341 Misses 10 10 ``` | [Impacted Files](https://codecov.io/gh/filtron/MarkovKernels.jl/pull/70?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Filip+Tronarp+) | Coverage Δ | | |---|---|---| | [src/covariance\_parameter.jl](https://codecov.io/gh/filtron/MarkovKernels.jl/pull/70?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Filip+Tronarp+#diff-c3JjL2NvdmFyaWFuY2VfcGFyYW1ldGVyLmps) | `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=Filip+Tronarp+). 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=Filip+Tronarp+)

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