fix(types): add type for serverMiddleware object format

[danielroe]

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

This adds the necessary type for the new feature added in #6414

Resolves: #8168

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly. (PR: #)
• I have added tests to cover my changes (if not applicable, please state why)
• All new and existing tests are passing.

[codecov-io]

Codecov Report

Merging #8182 into dev will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##              dev    #8182   +/-   ##
=======================================
  Coverage   68.92%   68.92%           
=======================================
  Files          91       91           
  Lines        3855     3855           
  Branches     1049     1049           
=======================================
  Hits         2657     2657           
  Misses        973      973           
  Partials      225      225           

Flag	Coverage Δ
#unittests	68.92% <ø> (ø)

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