Add job to push lib(s) in a new commit

.github/workflows/build-libs.yml

@@ -1,10 +1,16 @@
-name: Build ASDF lib and run tests
-# TODO: only pull_request?
-on: [push]
+name: Build PortAudio lib
+on:
+  push:
+    branches-ignore:
+      - master
+permissions:
+  # This is needed to push the changes back to the repo:
+  contents: write
 jobs:
   windows:
     runs-on: windows-2022
     # TODO: matrix with x64 and Win32
+    # TODO: with and without ASIO
     steps:
       - name: checkout portaudio
         uses: actions/checkout@v4
@@ -34,4 +40,18 @@ jobs:
 
 # TODO: macOS universal dylib
 
-# TODO: commit and push DLLs and dylib
+  push:
+    runs-on: ubuntu-latest
+    needs: [windows]
+    steps:
+      - name: Clone Git repository
+        uses: actions/checkout@v4
+      - name: Retrieve x64 DLL
+        uses: actions/download-artifact@v3
+        with:
+          name: windows-x64-dll
+      - name: Commit and push binaries (if there are changes)
+        run: |
+          git config --global user.name 'github-actions[bot]'
+          git config --global user.email 'github-actions[bot]@users.noreply.github.com'
+          git commit -am "Update binaries" && git push || true