deny.toml: Added skips for some duplicate dependencies in Cargo.lock

With the bump to wgpu 22.1, the hashbrown, syn, and bitflag
crates all trigger `cargo deny` due to multiple versions being found
in Cargo.lock. Different top-level dependencies are depending on different major
versions of these crates, and the top-level dependencies are all the most
recent version, so I don't think there's anything we can do to dedup these.

deny.toml

@@ -11,6 +11,9 @@ allow = [
 [bans]
 multiple-versions = "deny"
 skip = [
+    { name = "syn", version = "2.0.82" },
+    { name = "bitflags", version = "1.3.2" },
+    { name = "hashbrown", version = "0.14.5" },
 ]
 skip-tree = [
     { name = "winit", version = "0.27.5" },
@@ -26,4 +29,4 @@ ignore = [
 
 [sources]
 unknown-registry = "deny"
-unknown-git = "allow"
+unknown-git = "allow"