chore: bump rust from bf3368a to df6ca8f in /dogfood/coder (#21682)

Bumps rust from `bf3368a` to `df6ca8f`.


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dogfood/coder/Dockerfile

@@ -1,5 +1,5 @@
 # 1.86.0
-FROM rust:slim@sha256:bf3368a992915f128293ac76917ab6e561e4dda883273c8f5c9f6f8ea37a378e AS rust-utils
+FROM rust:slim@sha256:df6ca8f96d338697ccdbe3ccac57a85d2172e03a2429c2d243e74f3bb83ba2f5 AS rust-utils
 # Install rust helper programs
 ENV CARGO_INSTALL_ROOT=/tmp/
 # Use more reliable mirrors for Debian packages