Build macOS releases (#2198)

* Add macOS release target
* Update ubuntu runner

Ubuntu 16.04 runner environment is deprecated
https://github.blog/changelog/2021-04-29-github-actions-ubuntu-16-04-lts-virtual-environment-will-be-removed-on-september-20-2021/

.github/workflows/upload_binary.yml

@@ -11,16 +11,20 @@ jobs:
       fail-fast: false
       matrix:
         python-version: [3.7]
-        os: [ubuntu-16.04, windows-2019]
+        os: [windows-2019, ubuntu-20.04, macos-latest]
         include:
           - os: windows-2019
             pathsep: ";"
-            executable_suffix: ".exe"
+            asset_name: black_windows.exe
             executable_mime: "application/vnd.microsoft.portable-executable"
-          - os: ubuntu-16.04
+          - os: ubuntu-20.04
             pathsep: ":"
-            executable_suffix: ".elf"
+            asset_name: black_linux
             executable_mime: "application/x-executable"
+          - os: macos-latest
+            pathsep: ":"
+            asset_name: black_macos
+            executable_mime: "application/x-mach-binary"
 
     steps:
       - uses: actions/checkout@v2
@@ -38,7 +42,7 @@ jobs:
 
       - name: Build binary
         run: |
-          python -m PyInstaller -F --name black${{ matrix.executable_suffix }} --add-data 'src/blib2to3${{ matrix.pathsep }}blib2to3' src/black/__main__.py
+          python -m PyInstaller -F --name ${{ matrix.asset_name }} --add-data 'src/blib2to3${{ matrix.pathsep }}blib2to3' src/black/__main__.py
 
       - name: Upload binary as release asset
         uses: actions/upload-release-asset@v1
@@ -46,6 +50,6 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
           upload_url: ${{ github.event.release.upload_url }}
-          asset_path: dist/black${{ matrix.executable_suffix }}
-          asset_name: black${{ matrix.executable_suffix }}
+          asset_path: dist/${{ matrix.asset_name }}
+          asset_name: ${{ matrix.asset_name }}
           asset_content_type: ${{ matrix.executable_mime }}

CHANGES.md

@@ -13,6 +13,10 @@
 - Add a lower bound for the `aiohttp-cors` dependency. Only 0.4.0 or higher is
   supported. (#2231)
 
+### _Packaging_
+
+- Release self-contained macOS binaries as part of the GitHub release pipeline (#2198)
+
 ### Documentation
 
 - Fix typos discovered by codespell (#2228)