fix: mem leak

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (e354f85) 80.83% compared to head (125dfb5) 80.81%.

Files	Patch %	Lines
taos/cinterface.py	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #245 +/- ## ========================================== - Coverage 80.83% 80.81% -0.03% ========================================== Files 20 20 Lines 2708 2710 +2 ========================================== + Hits 2189 2190 +1 - Misses 519 520 +1 ```

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