Bump alpine from 3.14.0 to 3.18.4 in /docker/ci/alpine

Bumps alpine from 3.14.0 to 3.18.4.

---
updated-dependencies:
- dependency-name: alpine
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

docker/ci/alpine/Dockerfile

@@ -1,5 +1,5 @@
 # while using circle we'll use circle's base image.
-FROM alpine:3.14.0@sha256:234cb88d3020898631af0ccbbcca9a66ae7306ecd30c9720690858c1b007d2a0 AS setup_ci_alpine
+FROM alpine:3.18.4@sha256:eece025e432126ce23f223450a0326fbebde39cdf496a85d8c016293fc851978 AS setup_ci_alpine
 
 WORKDIR /diem
 COPY rust-toolchain /diem/rust-toolchain