azure pipelines -> github actions

.github/actions/pre-test/action.yml

@@ -0,0 +1,41 @@
+inputs:
+  env:
+    default: ${{ matrix.env }}
+
+runs:
+  using: composite
+  steps:
+  - name: setup (windows)
+    shell: bash
+    if: runner.os == 'Windows'
+    run: |
+      set -x
+
+      echo 'TEMP=C:\TEMP' >> "$GITHUB_ENV"
+
+      echo "$CONDA\Scripts" >> "$GITHUB_PATH"
+
+      echo 'C:\Strawberry\perl\bin' >> "$GITHUB_PATH"
+      echo 'C:\Strawberry\perl\site\bin' >> "$GITHUB_PATH"
+      echo 'C:\Strawberry\c\bin' >> "$GITHUB_PATH"
+
+      testing/get-dart.sh
+      pwsh testing/get-r.ps1
+  - name: setup (linux)
+    shell: bash
+    if: runner.os == 'Linux'
+    run: |
+      set -x
+
+      sudo apt-get update
+      sudo apt-get install -y --no-install-recommends \
+        lua5.3 \
+        liblua5.3-dev \
+        luarocks \
+        r-base
+
+      testing/get-coursier.sh
+      testing/get-dart.sh
+      testing/get-swift.sh
+  - uses: asottile/workflows/.github/actions/latest-git@v1.2.0
+    if: inputs.env == 'py38' && runner.os == 'Linux'