Add 0.9.1 entry to changelog

[roblim]

No description provided.

[coveralls]

Coverage remained the same at 77.677% when pulling 61cb267 on bugfix/missing-datasource-key-in-batch-kwargs into 8331828 on develop.

[codecov]

Codecov Report

Merging #1102 into develop will not change coverage by %.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           develop    #1102   +/-   ##
========================================
  Coverage    77.66%   77.66%           
========================================
  Files          103      103           
  Lines        11648    11648           
========================================
  Hits          9047     9047           
  Misses        2601     2601           

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