Added macOS workflow.

.github/workflows/functest.yml

@@ -2,10 +2,17 @@ name: functest
 
 on: [push, workflow_dispatch]
 
+defaults:
+  run:
+    shell: bash
+
 jobs:
   functest:
     name: Functional Test
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-12, ubuntu-22.04]
     steps:
       - uses: actions/checkout@v4
       - run: ./install.sh

README.md

@@ -26,7 +26,7 @@ On Windows, these are available natively via [MSYS2](https://www.msys2.org) and
 [WSL](https://learn.microsoft.com/en-us/windows/wsl/about). On macOS, they can be installed using
 [Homebrew](https://brew.sh/); however, their Apple-specific variants provided by
 [Xcode](https://apps.apple.com/app/xcode/id497799835) should also be fine. I am fairly sure that this will work on
-macOS, though I don't have a Mac to test it.
+macOS, though I don't have a Mac to test it. (I'm trying to figure out how to use a macOS runner on GitHub Actions.)
 
 The installation commands mentioned below must be entered in
 * the terminal if you are on Linux/macOS, or