fix SIR example

[rakvat]

This fixes the SIR example for me.

Might fix #1026

[Tortar]

thanks a lot!! We actually track the step of the simulation through abmtime so I update your fix with it :-)

[Tortar]

Let's see if on the online docs everything works fine now after it builds

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.50%. Comparing base (8b5b456) to head (31e9017).
Report is 109 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1029       +/-   ##
===========================================
+ Coverage   70.12%   86.50%   +16.38%     
===========================================
  Files          42       39        -3     
  Lines        2718     2550      -168     
===========================================
+ Hits         1906     2206      +300     
+ Misses        812      344      -468     

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