Fix warnings and cargo deny issues

.github/workflows/rust.yml

@@ -157,7 +157,7 @@ jobs:
         cargo afl check --bin fuzz_webp
         cargo afl check --bin fuzz_pnm
       env:
-        RUSTFLAGS: "-Znew-llvm-pass-manager=no"
+        RUSTFLAGS: ""
 
   build_fuzz_cargo-fuzz:
     name: "Fuzz targets (cargo-fuzz)"

deny.toml

@@ -26,6 +26,7 @@ wildcards = "allow" # at least until https://github.com/EmbarkStudios/cargo-deny
 deny = []
 skip = []
 skip-tree = [
+    { name = "flate2", version = "=1.0.24" }, # until a new version is published
     { name = "criterion" },  # dev-dependency
     { name = "quickcheck" }, # dev-dependency
 ]

src/dynimage.rs

@@ -1332,7 +1332,7 @@ mod test {
         // ensures that DynamicImage implements Default (if it didn't, this would cause a compile error).
         #[derive(Default)]
         struct Foo {
-            image: super::DynamicImage,
+            _image: super::DynamicImage,
         }
     }