Silent some clippy warnings (#924)

* allow(clippy::upper_case_acronyms) for rust enum entries that match
  SQLite constants.
* allow(clippy::needless_return) for collation_needed_callback until we
  find a way to propagate the error.

src/hooks.rs

@@ -13,6 +13,7 @@ use crate::{Connection, InnerConnection};
 #[derive(Clone, Copy, Debug, PartialEq)]
 #[repr(i32)]
 #[non_exhaustive]
+#[allow(clippy::upper_case_acronyms)]
 pub enum Action {
     /// Unsupported / unexpected action
     UNKNOWN = -1,