chore(deps): update alpine docker digest to 4b7ce07

Author: renovate[bot]

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine@sha256:4bcff63911fcb4448bd4fdacec207030997caf25e9bea4045fa6c8c44de311d1 AS builder
+FROM alpine@sha256:4b7ce07002c69e8f3d704a9c5d6fd3053be500b7f1c69fc0d80990c2ad8dd412 AS builder
 
 # imapfilter_spec can be a specific commit or a version tag
 ARG imapfilter_spec=master
@@ -14,7 +14,7 @@ RUN apk --no-cache add lua openssl pcre git \
     && git checkout "${imapfilter_spec}" \
     && make && make install
 
-FROM alpine@sha256:4bcff63911fcb4448bd4fdacec207030997caf25e9bea4045fa6c8c44de311d1
+FROM alpine@sha256:4b7ce07002c69e8f3d704a9c5d6fd3053be500b7f1c69fc0d80990c2ad8dd412
 
 # create an empty config.lua to prevent an error when running imapfilter directly
 RUN adduser -D -u 1001 imapfilter \