Upgrade to Rust 1.83 (#9511)

## Summary

A lot of good new lints, and most importantly, error stabilizations. I
tried to find a few usages of the new stabilizations, but I'm sure there
are more.

IIUC, this _does_ require bumping our MSRV.

crates/uv-settings/src/lib.rs

@@ -50,14 +50,7 @@ impl FilesystemOptions {
                 Ok(Some(Self(options)))
             }
             Err(Error::Io(err)) if err.kind() == std::io::ErrorKind::NotFound => Ok(None),
-            Err(_) if !dir.is_dir() => {
-                // Ex) `XDG_CONFIG_HOME=/dev/null`
-                tracing::debug!(
-                    "User configuration directory `{}` does not exist or is not a directory",
-                    dir.display()
-                );
-                Ok(None)
-            }
+            Err(Error::Io(err)) if err.kind() == std::io::ErrorKind::NotADirectory => Ok(None),
             Err(err) => Err(err),
         }
     }