False positive py/uninitialized-local-variable

**Description of the false positive**

**Code samples or links to source code**

```python
class Foo:
def foo(self, a, b, c=0):
start = 0
visible = not (a == b and c)
end = start if visible else None
return end

```

CodeQL Version: 2.18.3

Alert : Local variable 'visible' may be used before it is initialized.

I suspect that the issue is caused by EssaVariable being unable to locate the assignment statement for the variable visible, but I'm not sure how to modify the ql statement.

Review the py/uninitialized-local-variable query and its EssaVariable handling against the supplied Python sample. Confirm that the false alert about visible no longer appears for this code while the intended uninitialized-local-variable detection remains intact.

索引モデルが issue の本文から書いたものです。