Change Alpine package mirror

The default package mirror is having some trouble with package
signatures for 32-bit architectures. A solution is to change
to another one. More info in issue [#70][1].

[1]: #70

Author: JonasAlfredsson

src/Dockerfile-alpine

@@ -3,6 +3,10 @@ LABEL maintainer="Jonas Alfredsson <jonas.alfredsson@protonmail.com>"
 
 # Do a single run command to make the intermediary containers smaller.
 RUN set -ex && \
+# The default mirror has some issues with bad sigantures for the 32-bit
+# packages, so let's use another one until it is fixed.
+    echo 'http://dl-2.alpinelinux.org/alpine/v3.13/main' > /etc/apk/repositories && \
+    echo 'http://dl-2.alpinelinux.org/alpine/v3.13/community' >> /etc/apk/repositories && \
 # Install packages necessary during the build phase (for all architectures).
     apk add --no-cache \
         cargo \
@@ -19,7 +23,7 @@ RUN set -ex && \
         sed \
     && \
 # Because of the bug mentioned in issue #42 we must use Bash <5.1.x for now.
-    echo 'http://dl-cdn.alpinelinux.org/alpine/v3.12/main' >> /etc/apk/repositories && \
+    echo 'http://dl-2.alpinelinux.org/alpine/v3.12/main' >> /etc/apk/repositories && \
     apk add --no-cache 'bash<5.1' && \
 # Install the latest version of PIP, Setuptools and Wheel.
     curl -L 'https://bootstrap.pypa.io/get-pip.py' | python3 && \