CI: Add darwin-arm64 via MacStadium-based runner

.github/workflows/ci-darwin-arm64v8.yml

@@ -0,0 +1,27 @@
+name: CI (MacStadium)
+on:
+  - push
+  - pull_request
+jobs:
+  CI:
+    runs-on: macos-m1
+    defaults:
+      run:
+        shell: /usr/bin/arch -arch arm64e /bin/bash -l {0}
+    steps:
+      - name: Dependencies
+        uses: actions/setup-node@v2
+        with:
+          node-version: 16
+          architecture: arm64
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Install
+        run: npm install --build-from-source --unsafe-perm
+      - name: Test
+        run: npm test
+      - name: Prebuild
+        if: startsWith(github.ref, 'refs/tags/')
+        env:
+          prebuild_upload: ${{ secrets.GITHUB_TOKEN }}
+        run: npx prebuild --runtime napi --target 5

.github/workflows/ci.yml

@@ -1,3 +1,4 @@
+name: CI (GitHub)
 on:
   - push
   - pull_request

docs/install.md

@@ -18,12 +18,13 @@ Ready-compiled sharp and libvips binaries are provided for use with
 Node.js v10+ on the most common platforms:
 
 * macOS x64 (>= 10.13)
+* macOS ARM64
 * Linux x64 (glibc >= 2.17, musl >= 1.1.24)
 * Linux ARM64 (glibc >= 2.29, musl >= 1.1.24)
 * Windows x64
 * Windows x86
 
-An ~7.5MB tarball containing libvips and its most commonly used dependencies
+An ~7MB tarball containing libvips and its most commonly used dependencies
 is downloaded via HTTPS and stored within `node_modules/sharp/vendor` during `npm install`.
 
 This provides support for the
@@ -31,7 +32,6 @@ JPEG, PNG, WebP, AVIF, TIFF, GIF (input) and SVG (input) image formats.
 
 The following platforms have prebuilt libvips but not sharp:
 
-* macOS ARM64
 * Linux ARMv6
 * Linux ARMv7 (glibc >= 2.28)
 * Windows ARM64

install/libvips.js

@@ -24,6 +24,7 @@ const minimumGlibcVersionByArch = {
 
 const hasSharpPrebuild = [
   'darwin-x64',
+  'darwin-arm64',
   'linux-arm64',
   'linux-x64',
   'linuxmusl-x64',