Fix restrictive input check in pearson corr coef

[SkafteNicki]

What does this PR do?

Fixes #1647
One of the check of the input is a bit too restrictive, such that only input of the form [N,1] is allowed but not [N,]. Changes the check to allow both.

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• Did you write any new necessary tests?

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[codecov]

Codecov Report

Merging #1649 (6ab2aad) into master (685391d) will decrease coverage by 49%.
The diff coverage is 10%.

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #1649     +/-   ##
========================================
- Coverage      89%     39%    -49%     
========================================
  Files         228     228             
  Lines       12363   12450     +87     
========================================
- Hits        10945    4892   -6053     
- Misses       1418    7558   +6140