GitHub Actions: Split Windows and macOS workflows

Somehow `$(find ./build -name ninja -or -name ninja.exe)` stopped
working on Windows.
diff --git a/.github/workflows/macos.yml b/.github/workflows/macos.yml
new file mode 100644
index 0000000..2a7c100
--- /dev/null
+++ b/.github/workflows/macos.yml
@@ -0,0 +1,49 @@
+name: macOS
+
+on:
+  pull_request:
+  push:
+  release:
+    types: published
+
+jobs:
+  build:
+    runs-on: macOS-latest
+
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: Install dependencies
+      run: brew install re2c p7zip cmake
+
+    - name: Build ninja
+      shell: bash
+      run: |
+        mkdir build && cd build
+        cmake -DCMAKE_BUILD_TYPE=Release ..
+        cmake --build . --parallel --config Release
+        ctest -vv
+
+    - name: Create ninja archive
+      shell: bash
+      run: |
+        mkdir artifact
+        7z a artifact/ninja-mac.zip ./build/ninja
+
+    # Upload ninja binary archive as an artifact
+    - name: Upload artifact
+      uses: actions/upload-artifact@v1
+      with:
+        name: ninja-binary-archives
+        path: artifact
+
+    - name: Upload release asset
+      if: github.event.action == 'published'
+      uses: actions/upload-release-asset@v1.0.1
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      with:
+        upload_url: ${{ github.event.release.upload_url }}
+        asset_path: ./artifact/ninja-mac.zip
+        asset_name: ninja-mac.zip
+        asset_content_type: application/zip
diff --git a/.github/workflows/release-ninja-binaries.yml b/.github/workflows/release-ninja-binaries.yml
deleted file mode 100644
index 8c1e0af..0000000
--- a/.github/workflows/release-ninja-binaries.yml
+++ /dev/null
@@ -1,64 +0,0 @@
-name: Release Ninja Binaries
-
-on:
-  pull_request:
-  push:
-  release:
-    types: published
-
-jobs:
-  build:
-    runs-on: ${{ matrix.os }}
-    strategy:
-      matrix:
-        os: [macOS-latest, windows-latest]
-        include:
-          - os: macOS-latest
-            zip_name: ninja-mac
-          - os: windows-latest
-            zip_name: ninja-win
-
-    steps:
-    - uses: actions/checkout@v1
-
-    # Install OS specific dependencies
-    - name: Install macOS dependencies
-      if: matrix.os == 'macOS-latest'
-      run: brew install re2c p7zip cmake
-    - name: Install Windows dependencies
-      if: matrix.os == 'windows-latest'
-      run: choco install re2c
-
-    - name: Build ninja
-      shell: bash
-      run: |
-        mkdir build && cd build
-        cmake -DCMAKE_BUILD_TYPE=Release ..
-        cmake --build . --parallel --config Release
-        ctest -vv
-
-    - name: Create ninja archive
-      shell: bash
-      env:
-        ZIP_NAME: ${{ matrix.zip_name }}
-      run: |
-        mkdir artifact
-        7z a artifact/${ZIP_NAME}.zip $(find ./build -name ninja -or -name ninja.exe)
-
-    # Upload ninja binary archive as an artifact
-    - name: Upload artifact
-      uses: actions/upload-artifact@v1
-      with:
-        name: ninja-binary-archives
-        path: artifact
-
-    - name: Upload release asset
-      if: github.event.action == 'published'
-      uses: actions/upload-release-asset@v1.0.1
-      env:
-        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-      with:
-        upload_url: ${{ github.event.release.upload_url }}
-        asset_path: ./artifact/${{ matrix.zip_name }}.zip
-        asset_name: ${{ matrix.zip_name }}.zip
-        asset_content_type: application/zip
diff --git a/.github/workflows/windows.yml b/.github/workflows/windows.yml
new file mode 100644
index 0000000..bdec6c9
--- /dev/null
+++ b/.github/workflows/windows.yml
@@ -0,0 +1,49 @@
+name: Windows
+
+on:
+  pull_request:
+  push:
+  release:
+    types: published
+
+jobs:
+  build:
+    runs-on: windows-latest
+
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: Install dependencies
+      run: choco install re2c
+
+    - name: Build ninja
+      shell: bash
+      run: |
+        mkdir build && cd build
+        cmake -DCMAKE_BUILD_TYPE=Release ..
+        cmake --build . --parallel --config Release
+        ctest -vv
+
+    - name: Create ninja archive
+      shell: bash
+      run: |
+        mkdir artifact
+        7z a artifact/ninja-win.zip ./build/Release/ninja.exe
+
+    # Upload ninja binary archive as an artifact
+    - name: Upload artifact
+      uses: actions/upload-artifact@v1
+      with:
+        name: ninja-binary-archives
+        path: artifact
+
+    - name: Upload release asset
+      if: github.event.action == 'published'
+      uses: actions/upload-release-asset@v1.0.1
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      with:
+        upload_url: ${{ github.event.release.upload_url }}
+        asset_path: ./artifact/ninja-win.zip
+        asset_name: ninja-win.zip
+        asset_content_type: application/zip