Bump alpine from 3.15.1 to 3.15.2 in /.ci/docker-ci/alpine (#808)

Bumps alpine from 3.15.1 to 3.15.2.

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

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.ci/docker-ci/alpine/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.15.1
+FROM alpine:3.15.2
 
 LABEL maintainer="mail@sobolevn.me"
 LABEL vendor="git-secret team"