Switch unit tests to C++20 on MSVC and fix range support detection

[bernhardmgruber]

No description provided.

[codecov]

Codecov Report

Merging #443 (cb4cae2) into develop (021efe5) will not change coverage.
The diff coverage is n/a.

❗ Current head cb4cae2 differs from pull request most recent head 5fc23a7. Consider uploading reports for the commit 5fc23a7 to get more accurate results

@@           Coverage Diff            @@
##           develop     #443   +/-   ##
========================================
  Coverage    99.21%   99.21%           
========================================
  Files           58       58           
  Lines         5200     5200           
========================================
  Hits          5159     5159           
  Misses          41       41           

Impacted Files	Coverage Δ
include/llama/ArrayIndexRange.hpp	96.77% <ø> (ø)
include/llama/View.hpp	97.10% <ø> (ø)
include/llama/VirtualRecord.hpp	100.00% <ø> (ø)

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