Python: Update tree-sitter dependency

Updates the Python extractor to depend on version 0.24.7 of tree-sitter
(and 0.12.0 of tree-sitter-graph).

A few changes were needed in order to make the code build and run after
updating the dependencies:

- In `main.rs`, the `Language` parameter is now passed as a reference.
- In `python.tsg`, many queries had captures that were not actually used
in the body of the stanza. This is no longer allowed (unless the
captures start with an underscore), as it may indicate an error. To fix
this, I added underscores in the appropriate places (and verified that
none of these unused captures were in fact bugs).

python/extractor/tsg-python/src/main.rs

@@ -502,7 +502,7 @@ fn main() -> Result<()> {
     let source_path = Path::new(matches.get_one::<String>("source").unwrap());
     let language = tsp::language();
     let mut parser = Parser::new();
-    parser.set_language(language)?;
+    parser.set_language(&language)?;
     // Statically include `python.tsg`:
     let tsg = if matches.contains_id("tsg") {
         std::fs::read(&tsg_path).with_context(|| format!("Error reading TSG file {}", tsg_path))?