chore(deps): update docker.io/rust docker tag to v1.91 (#1374)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| docker.io/rust | stage | minor | `1.90` -> `1.91` |

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rust/otap-dataflow/Dockerfile

@@ -7,7 +7,7 @@
 # with the arrow enabled go collector build files in the repo root, the image
 # must be built with additional --build-context flags as follows:
 # docker build --build-context otel-arrow=../../ -f Dockerfile -t df_engine .
-FROM --platform=$BUILDPLATFORM docker.io/rust:1.90@sha256:e227f20ec42af3ea9a3c9c1dd1b2012aa15f12279b5e9d5fb890ca1c2bb5726c AS dataflow-build
+FROM --platform=$BUILDPLATFORM docker.io/rust:1.91@sha256:087fe682ef35ecac5b110dbf35cafade2cbd487f8a86e9390203f77f962887cf AS dataflow-build
 WORKDIR /build/rust/dataflow
 ARG BUILDPLATFORM
 ARG TARGETPLATFORM