Update alpine Docker tag to v3.15.0

docker/Dockerfile.builder

@@ -1,6 +1,6 @@
 # vim: filetype=dockerfile
 # Our entire toolchain runs in alpine
-FROM alpine:3.13.5 AS builder
+FROM alpine:3.15.0 AS builder
 
 ENV PATH "$PATH:/root/.cargo/bin"
 # Needed for proper compiling of openssl-dev

docker/Dockerfile.rel

@@ -34,7 +34,7 @@ RUN yarn install && \
 
 
 # Now, we create the actual image
-FROM alpine:3.13.5
+FROM alpine:3.15.0
 COPY ./docker/crontab /var/spool/cron/crontabs/fej
 
 # Install some dynamic libraries needed for everything to work