update to latest Rust

defs.bzl

@@ -19,7 +19,7 @@ def setup_deps():
 
     rust_repositories(
         edition = "2018",
-        version = "1.48.0",
+        version = "1.51.0",
     )
 
     raze_fetch_remote_crates()

rslib/src/backend/mod.rs

@@ -3,7 +3,6 @@
 
 // infallible backend methods still return a result
 #![allow(clippy::unnecessary_wraps)]
-#![allow(clippy::unknown_clippy_lints)]
 
 mod adding;
 mod card;

rslib/src/decks/mod.rs

@@ -863,6 +863,8 @@ mod test {
         fn n(s: &str) -> String {
             s.replace(":", "\x1f")
         }
+
+        #[allow(clippy::unnecessary_wraps)]
         fn n_opt(s: &str) -> Option<String> {
             Some(n(s))
         }

rslib/src/media/files.rs

@@ -122,10 +122,6 @@ pub(crate) fn normalize_nfc_filename(mut fname: Cow<str>) -> Cow<str> {
 /// On Apple devices, the filename may be stored on disk in NFD encoding,
 /// but can be accessed as NFC. On these devices, if the filename
 /// is otherwise valid, the filename is returned as NFC.
-///
-/// First two lints can be removed after updating to 1.51
-#[allow(clippy::unknown_clippy_lints)]
-#[allow(clippy::collapsible_if)]
 #[allow(clippy::collapsible_else_if)]
 pub(super) fn filename_if_normalized(fname: &str) -> Option<Cow<str>> {
     if cfg!(target_vendor = "apple") {