Update Docker image to Alpine 3.13

Dockerfile

@@ -1,12 +1,7 @@
-FROM alpine:3.12
+FROM alpine:3.13
 
 ARG TARGETARCH=amd64
 
-RUN echo $'\
-@edge http://dl-cdn.alpinelinux.org/alpine/edge/main\n\
-@edge http://dl-cdn.alpinelinux.org/alpine/edge/testing\n\
-@edge http://dl-cdn.alpinelinux.org/alpine/edge/community' >> /etc/apk/repositories
-
 RUN apk add --no-cache \
       python3 py3-pip py3-setuptools py3-wheel \
       py3-virtualenv \
@@ -14,12 +9,13 @@ RUN apk add --no-cache \
       py3-aiohttp \
       py3-magic \
       py3-ruamel.yaml \
-      py3-commonmark@edge \
+      py3-commonmark \
       # Other dependencies
+      py3-cryptography \
+      py3-protobuf \
       ca-certificates \
       su-exec \
       # encryption
-      libressl \
       olm-dev \
       py3-cffi \
       py3-pycryptodome \
@@ -27,14 +23,13 @@ RUN apk add --no-cache \
       py3-future \
       bash \
       curl \
-      jq && \
-  curl -sLo yq https://github.com/mikefarah/yq/releases/download/3.3.2/yq_linux_${TARGETARCH} && \
-  chmod +x yq && mv yq /usr/bin/yq
+      jq \
+      yq
 
 COPY requirements.txt /opt/mautrix-signal/requirements.txt
 COPY optional-requirements.txt /opt/mautrix-signal/optional-requirements.txt
 WORKDIR /opt/mautrix-signal
-RUN apk add --virtual .build-deps python3-dev libffi-dev libressl-dev build-base \
+RUN apk add --virtual .build-deps python3-dev libffi-dev build-base \
  && pip3 install -r requirements.txt -r optional-requirements.txt \
  && apk del .build-deps