Bump alpine from 3.14 to 3.15.0 (#397)

Bumps alpine from 3.14 to 3.15.0.

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

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

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.14
+FROM alpine:3.15.0
 
 # 'nobody' user in alpine
 USER 65534