build: Use tmpfs for cargo cache

That seems to workaround rust-lang/cargo#8719.

.github/bin/get-buildx-args

@@ -16,6 +16,10 @@ if [ "$1" != "publish" ] ; then
     echo --cache-to "type=local,dest=/tmp/.buildx-cache/$MATRIX_ARCHITECTURE"
 fi
 
+# Workaround for https://github.com/rust-lang/cargo/issues/8719,
+# see Dockerfile as well
+echo --allow security.insecure
+
 if [ "$1" = "load" ] ; then
     # Ommit list of platforms loading, see https://github.com/docker/buildx/issues/59
     echo --output=type=docker

Dockerfile

@@ -2,6 +2,10 @@ FROM debian:bullseye-20211115-slim
 ENV VERSION 4.9.1
 ARG TARGETARCH
 
+# Workaround for https://github.com/rust-lang/cargo/issues/8719,
+# see below in the Dockerfile and .github/bin/get-buildx-args as well
+# syntax = docker/dockerfile:experimental
+
 LABEL name="Weblate"
 LABEL version=$VERSION
 LABEL maintainer="Michal Čihař <[email protected]>"
@@ -46,6 +50,10 @@ ENV PYTHONUNBUFFERED=1
 
 COPY requirements.txt patches /usr/src/weblate/
 
+# Workaround for https://github.com/rust-lang/cargo/issues/8719,
+# see top Dockerfile and .github/bin/get-buildx-args as well
+RUN mkdir -p /root/.cargo && chmod 777 /root/.cargo && mount -t tmpfs none /root/.cargo
+
 # Install dependencies
 # hadolint ignore=DL3008,DL3013,SC2046
 RUN \
@@ -110,11 +118,6 @@ RUN \
     fi \
   && curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y \
   && source $HOME/.cargo/env \
-  # Handle an extremely specific issue when building the cryptography package for \
-  # 32-bit architectures within QEMU running on a 64-bit host (issue #30). \
-  && if [ "${BUILDX_QEMU_ENV}" = "true" -a "$(getconf LONG_BIT)" = "32" ] ; then \
-        sed -i s/^cryptography==/cryptography==3.3.2/ /usr/src/weblate/requirements.txt ; \
-  fi \
   && python3 -m pip install --no-cache-dir --upgrade $(grep -E '^(pip|wheel|setuptools)==' /usr/src/weblate/requirements.txt) \
   && python3 -m pip install --no-cache-dir --no-binary :all: $(grep ^cffi== /usr/src/weblate/requirements.txt) \
   && case "$VERSION" in \
@@ -159,7 +162,8 @@ RUN \
   && apt-get -y autoremove \
   && apt-get clean \
   && rustup self uninstall -y \
-  && rm -rf /root/.cache /tmp/* /var/lib/apt/lists/*
+  && rm -rf /root/.cache /tmp/* /var/lib/apt/lists/* \
+  && umount /root/.cargo && rmdir /root/.cargo
 
 # Apply hotfixes on Weblate
 RUN find /usr/src/weblate -name '*.patch' -print0 | sort -z | \