fix: fix issue cancelling unpaid registration

[rpcross]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 88.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 88.73%. Comparing base (e16d568) to head (fcf1e96).
Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
ietf/meeting/utils.py	88.88%	1 Missing ??

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9170   +/-   ##
=======================================
  Coverage   88.72%   88.73%           
=======================================
  Files         321      321           
  Lines       41851    41860    +9     
=======================================
+ Hits        37134    37146   +12     
+ Misses       4717     4714    -3     

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