(🐞) Add the missing period in error message (#9485)
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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
I noticed that there should be a missing period added to some of the new
error messages for Unnecessary dunder call:
```
sandpit\test.py:6:16: PLC2801 Unnecessary dunder call to `__getattribute__`. Access attribute directly or use getattr built-in function..
```
## Test Plan
Static analysis of the implementation, as this has no existing test
cases.
