Updates for latest change in xrayvision

[samaloney]

• Remove no unnesary transpose from EM algorithm (due to fix in xrayvison)
• Update imaging demo
  • Units for pixel are now arcsec/pixel
  • Flare location in array indexing (v WCS) is [stix_max.Ty, six_max.Tx]

Only to be merged after TCDSolar/xrayvision/pull/58

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 72.57%. Comparing base (8867c2d) to head (3ad179f). Report is 9 commits behind head on main.

Files	Patch %	Lines
stixpy/imaging/em.py	0.00%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #115 +/- ## ========================================== + Coverage 72.53% 72.57% +0.03% ========================================== Files 31 31 Lines 1857 1856 -1 ========================================== Hits 1347 1347 + Misses 510 509 -1 ```

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