CI: migrate away from drone.io

.github/workflows/ci.yaml

@@ -199,3 +199,48 @@ jobs:
         else
           stack $STACK_ARGS test --bench --no-run-benchmarks --haddock --no-haddock-deps
         fi
+
+  i386:
+    runs-on: ubuntu-latest
+    container:
+      image: i386/ubuntu:bionic
+    steps:
+    - name: Install
+      run: |
+        apt-get update -y
+        apt-get install -y autoconf build-essential zlib1g-dev libgmp-dev curl libncurses5 libtinfo5 libncurses5-dev libtinfo-dev
+        curl --proto '=https' --tlsv1.2 -sSf https://get-ghcup.haskell.org | BOOTSTRAP_HASKELL_NONINTERACTIVE=1 BOOTSTRAP_HASKELL_INSTALL_NO_STACK=1 sh
+    - uses: actions/checkout@v1
+    - name: Test
+      run: |
+        source ~/.ghcup/env
+        cabal update
+        cabal test
+
+  # We use github.com/haskell self-hosted runners for ARM testing.
+  arm:
+    runs-on: [self-hosted, Linux, ARM64]
+    strategy:
+      fail-fast: true
+      matrix:
+        arch: [arm32v7, arm64v8]
+    steps:
+      - uses: docker://hasufell/arm64v8-ubuntu-haskell:focal
+        name: Cleanup
+        with:
+          args: "find . -mindepth 1 -maxdepth 1 -exec rm -rf -- {} +"
+
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - if: matrix.arch == 'arm32v7'
+        uses: docker://hasufell/arm32v7-ubuntu-haskell:focal
+        name: Run build (arm32v7 linux)
+        with:
+          args: sh -c "cabal update && cabal test"
+
+      - if: matrix.arch == 'arm64v8'
+        uses: docker://hasufell/arm64v8-ubuntu-haskell:focal
+        name: Run build (arm64v8 linux)
+        with:
+          args: sh -c "cabal update && cabal test"