MINOR: add result to onAfterMiddlware hook

[unclecheese]

Needed for snapshots, and seems like it could be useful in other contexts.

[codecov]

Codecov Report

Merging #258 into 3.2 will not change coverage by %.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##                3.2     #258   +/-   ##
=========================================
  Coverage     85.93%   85.93%           
  Complexity      969      969           
=========================================
  Files            61       61           
  Lines          2446     2446           
=========================================
  Hits           2102     2102           
  Misses          344      344           

Impacted Files	Coverage Δ	Complexity Δ
src/Manager.php	80.32% <100.00%> (ø)	76.00 <0.00> (ø)

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