Run qemu in tmpfs (#1707)

Author: ntkme

.github/workflows/ci.yml

@@ -315,10 +315,12 @@ jobs:
             --env "GH_TOKEN=$GH_TOKEN" \
             --env "GH_USER=$GH_USER" \
             --platform ${{ matrix.platform }} \
-            --volume "$PWD:$PWD" \
+            --mount type=bind,source="$PWD",target="$PWD" \
+            --mount type=tmpfs,destination=/root/.pub-cache \
+            --mount type=tmpfs,destination=/tmp \
             --workdir "$PWD" \
             docker.io/library/dart:latest \
-            /bin/sh -c "dart pub get && dart run grinder pkg-github-linux-${{ matrix.arch }}"
+            /bin/sh -c "cp -R . /tmp/workspace && cd /tmp/workspace && dart pub get && dart run grinder pkg-github-linux-${{ matrix.arch }}"
         env:
           GH_TOKEN: "${{ secrets.GH_TOKEN }}"
           GH_USER: sassbot