Bump frolvlad/alpine-python3 in /benchmarks/docker (#1121)

Bumps frolvlad/alpine-python3 from `d2b602c` to `8f6a520`.

---
updated-dependencies:
- dependency-name: frolvlad/alpine-python3
  dependency-type: direct:production
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

benchmarks/docker/Dockerfile-benchmark

@@ -1,4 +1,4 @@
-FROM frolvlad/alpine-python3@sha256:d2b602c49f332ab70060ecf2e3beae6f54efc4e163784620946fc04de8050c74
+FROM frolvlad/alpine-python3@sha256:8f6a5204dbb49a746185909a3543247fbf50bdaa6e8a0d933647b3c689f5e138
 
 RUN apk add docker openrc
 RUN rc-update add docker boot