(🐞) 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.

crates/ruff_linter/src/rules/pylint/rules/unnecessary_dunder_call.rs

@@ -283,15 +283,15 @@ impl DunderReplacement {
             "__delitem__" => Some(Self::MessageOnly("Use `del` statement")),
             "__divmod__" => Some(Self::MessageOnly("Use `divmod()` builtin")),
             "__format__" => Some(Self::MessageOnly(
-                "Use `format` builtin, format string method, or f-string.",
+                "Use `format` builtin, format string method, or f-string",
             )),
             "__fspath__" => Some(Self::MessageOnly("Use `os.fspath` function")),
             "__get__" => Some(Self::MessageOnly("Use `get` method")),
             "__getattr__" => Some(Self::MessageOnly(
-                "Access attribute directly or use getattr built-in function.",
+                "Access attribute directly or use getattr built-in function",
             )),
             "__getattribute__" => Some(Self::MessageOnly(
-                "Access attribute directly or use getattr built-in function.",
+                "Access attribute directly or use getattr built-in function",
             )),
             "__getitem__" => Some(Self::MessageOnly("Access item via subscript")),
             "__init__" => Some(Self::MessageOnly("Instantiate class directly")),
@@ -304,7 +304,7 @@ impl DunderReplacement {
             "__rpow__" => Some(Self::MessageOnly("Use ** operator or `pow()` builtin")),
             "__set__" => Some(Self::MessageOnly("Use subscript assignment")),
             "__setattr__" => Some(Self::MessageOnly(
-                "Mutate attribute directly or use setattr built-in function.",
+                "Mutate attribute directly or use setattr built-in function",
             )),
             "__setitem__" => Some(Self::MessageOnly("Use subscript assignment")),
             "__truncate__" => Some(Self::MessageOnly("Use `math.trunc()` function")),