Fix Quasi Newton for complex Manifolds

[kellertuer]

Or to be precise for the inner product that needs to be wrapped with real in one place.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (ebd4833) 99.62% compared to head (b80c9ae) 99.62%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #350 +/- ## ======================================= Coverage 99.62% 99.62% ======================================= Files 69 69 Lines 6398 6398 ======================================= Hits 6374 6374 Misses 24 24 ```

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