.github/workflows: add macOS build

.github/workflows/build-macos.yml

+---
+on:
+  workflow_dispatch:
+  push:
+    paths-ignore:
+      - 'android/**'
+      - 'build/**'
+      - 'doc/**'
+      - 'python/**'
+      - 'subprojects/**'
+      - 'systemd/**'
+      - 'win32/**'
+    branches:
+      - master
+      - actions
+  pull_request:
+    paths-ignore:
+      - 'android/**'
+      - 'build/**'
+      - 'doc/**'
+      - 'python/**'
+      - 'subprojects/**'
+      - 'systemd/**'
+      - 'win32/**'
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: macos-latest
+    steps:
+      - id: checkout
+        uses: actions/checkout@v2
+
+      - id: cache-ccache
+        uses: hendrikmuhs/ccache-action@v1
+        with:
+          key: ${{ matrix.os }}-${{ matrix.type }}
+
+      - name: Install dependencies
+        run: |
+          brew install \
+            fmt \
+            googletest \
+            icu4c \
+            ffmpeg \
+            libnfs \
+            yajl \
+            libupnp \
+            libid3tag \
+            chromaprint \
+            libsamplerate \
+            libsoxr \
+            flac \
+            opus \
+            libvorbis \
+            faad2 \
+            wavpack \
+            libmpdclient
+
+      - name: Meson Build
+        uses: BSFishy/meson-build@v1.0.3
+        with:
+          action: test
+          directory: output
+          setup-options: -Ddocumentation=disabled -Dtest=true
+          meson-version: 0.56.0