bump MSRV to 1.83 (#16294)

According to our new MSRV policy (see
https://github.com/astral-sh/ruff/issues/16370 ), bump our MSRV to 1.83
(N - 2), and autofix some new clippy lints.

crates/ruff_notebook/src/cell.rs

@@ -66,7 +66,7 @@ impl Cell {
                     .metadata
                     .vscode
                     .as_ref()
-                    .map_or(true, |vscode| vscode.language_id == "python") =>
+                    .is_none_or(|vscode| vscode.language_id == "python") =>
             {
                 &cell.source
             }