Update alpine Docker tag to v3.11

Author: renovate-bot

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.10@sha256:e4355b66995c96b4b468159fc5c7e3540fcef961189ca13fee877798649f531a AS builder
+FROM alpine:3.11@sha256:ddba4d27a7ffc3f86dd6c2f92041af252a1f23a8e742c90e6e1297bfa1bc0c45 AS builder
 
 ENV GIT_CRYPT_VERSION 0.6.0
 ENV GIT_CRYPT_CHECKSUM 777c0c7aadbbc758b69aff1339ca61697011ef7b92f1d1ee9518a8ee7702bb78
@@ -17,7 +17,7 @@ RUN curl -fSsL https://github.com/AGWA/git-crypt/archive/$GIT_CRYPT_VERSION.tar.
     && make \
     && make install PREFIX=/usr
 
-FROM alpine:3.10@sha256:e4355b66995c96b4b468159fc5c7e3540fcef961189ca13fee877798649f531a
+FROM alpine:3.11@sha256:ddba4d27a7ffc3f86dd6c2f92041af252a1f23a8e742c90e6e1297bfa1bc0c45
 
 RUN apk --update --no-cache add \
     git \