build(deps): bump alpine from 3.13.5 to 3.14.0

Bumps alpine from 3.13.5 to 3.14.0.

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

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

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.13.5
+FROM alpine:3.14.0
 
 ARG POSTFIX_PACKAGE_VERSION=3.5.10-r0
 # http://www.postfix.org/postconf.5.html#tls_append_default_CA