fix: fix regression in tpcbench.py

[andygrove]

Which issue does this PR close?

Fix regression introduced in #2491

Rationale for this change

Script fails without this fix

What changes are included in this PR?

How are these changes tested?

[comphead]

ouch, thanks for finding this

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.38%. Comparing base (f09f8af) to head (f03ee81).
⚠️ Report is 562 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2512      +/-   ##
============================================
+ Coverage     56.12%   58.38%   +2.25%     
- Complexity      976     1436     +460     
============================================
  Files           119      146      +27     
  Lines         11743    13502    +1759     
  Branches       2251     2350      +99     
============================================
+ Hits           6591     7883    +1292     
- Misses         4012     4389     +377     
- Partials       1140     1230      +90     

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