ci(deps): pin docker/dockerfile docker tag to ac85f38 (#448)

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| docker/dockerfile | syntax | pinDigest |  -> `ac85f38` |

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.github/workflows/build/Dockerfile

@@ -1,4 +1,4 @@
-# syntax=docker/dockerfile:1
+# syntax=docker/dockerfile:1@sha256:ac85f380a63b13dfcefa89046420e1781752bab202122f8f50032edf31be0021
 FROM --platform=$BUILDPLATFORM busybox:latest@sha256:3fbc632167424a6d997e74f52b878d7cc478225cffac6bc977eedfe51c7f4e79 AS env
 ARG TARGETPLATFORM
 ARG BINARY_NAME=rust-ci-test