Bump frolvlad/alpine-python3 in /benchmarks/docker (#1170)

Bumps frolvlad/alpine-python3 from `2d3eda5` to `c639c67`.

---
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@sha256:2d3eda5965d1017f1962674c33c62829541b653145376c54398b91704d503bac
+FROM frolvlad/alpine-python3@sha256:c639c67f9c20d5e9c64f9e277bc9706c40001085988376329c332b24b7cf94df
 
 RUN apk add docker openrc
 RUN rc-update add docker boot