Add a trailing newline to all .py.expect files (#3156)

This just re-formats all the `.py.expect` files with Black, both to add a trailing newline and be doubly-certain that they're correctly formatted.

I also ensured that we add a hard line break after each statement, and that we avoid including an extra newline in the generated Markdown (since the code should contain the exact expected newlines).

crates/ruff_python_formatter/src/lib.rs

@@ -208,7 +208,7 @@ mod tests {
     impl std::fmt::Display for CodeFrame<'_> {
         fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
             writeln!(f, "```{}", self.language)?;
-            writeln!(f, "{}", self.code)?;
+            write!(f, "{}", self.code)?;
             writeln!(f, "```")?;
             writeln!(f)
         }