fix mapping mpi int16

[mtar]

Description

Include a summary of the change/s.
Please also include relevant motivation and context. List any dependencies that are required for this change.

Issue/s resolved: #497

Changes proposed:

• corrected wrong mapping: SHORT_INT -> SHORT

Type of change

Remove irrelevant options:

• Bug fix (non-breaking change which fixes an issue)

Due Diligence

• All split configurations tested
• Multiple dtypes tested in relevant functions
• Documentation updated (if needed)
• Updated changelog.md under the title "Pending Additions"

Does this change modify the behaviour of other functions? If so, which?

no

[codecov]

Codecov Report

Merging #499 into master will not change coverage by %.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #499   +/-   ##
=======================================
  Coverage   96.60%   96.60%           
=======================================
  Files          65       65           
  Lines       13991    13991           
=======================================
  Hits        13516    13516           
  Misses        475      475           

Impacted Files	Coverage Δ
heat/core/communication.py	89.04% <ø> (ø)

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