blurmac: Update objc2 to 0.4.1 (#40113)

Bumps from 0.2.0 to 0.4.0, we have to temporarily duplicate
`objc2-encode`, but the next PR will finish the upgrade and unduplicate
that dependency.

Testing: No functionality changed, only a refactor

Signed-off-by: Ashwin Naren <arihant2math@gmail.com>

deny.toml

@@ -193,6 +193,9 @@ skip = [
     # really just a build dep, so not a large problem.
     "toml_datetime",
     "toml_edit",
+
+    # blurmac
+    "objc2-encode",
 ]
 
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