chore: Add repo-sync actions

.github/workflows/clang-format.yml

@@ -1,9 +1,6 @@
 name: test-clang-format
 
-on:
-  pull_request:
-    branches:
-      - master
+on: ["pull_request", "push"]
 
 jobs:
   build:

.github/workflows/osx.yml

@@ -1,10 +1,7 @@
 ---
 name: macOS build and test AWS Encryption SDK for C
 
-on:
-  pull_request:
-    branches:
-      - master
+on: ["pull_request", "push"]
 
 
 jobs:

.github/workflows/repo-sync.yml

@@ -0,0 +1,25 @@
+name: Repo Sync
+
+on:
+  workflow_dispatch:     # allows triggering this manually through the Actions UI
+
+jobs:
+  repo-sync:
+    name: Repo Sync
+    environment: repo-sync
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - uses: repo-sync/github-sync@v2
+      name: Sync repo to branch
+      with:
+        source_repo: ${{ secrets.SOURCE_REPO }}
+        source_branch: master
+        destination_branch: ${{ secrets.INTERMEDIATE_BRANCH }}
+        github_token: ${{ secrets.GITHUB_TOKEN }}
+    - uses: repo-sync/pull-request@v2
+      name: Create pull request
+      with:
+        source_branch: ${{ secrets.INTERMEDIATE_BRANCH }}
+        destination_branch: master
+        github_token: ${{ secrets.GITHUB_TOKEN }}