Set samples branch back to master (#803)

.github/workflows/check-samples-branch.yml

@@ -0,0 +1,22 @@
+on:
+  pull_request:
+    branches:
+    - master
+
+jobs:
+  check-samples-branch:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Check that samples branch refers to master.
+        run: |
+          $configPath = ".openpublishing.publish.config.json";
+          $config = Get-Content $configPath | ConvertFrom-Json;
+          $samplesRepo = $config.dependent_repositories | Where-Object {
+            $_.url -eq "https://github.com/microsoft/quantum"
+          }
+          if ($samplesRepo.branch -ne "master") {
+            Write-Host "::error file=$configPath::Samples repository branch is not set to master for a PR targeting master."
+            exit 1;
+          }
+        shell: pwsh

.openpublishing.publish.config.json

@@ -72,7 +72,7 @@
     {
       "path_to_root": "articles/quantum",
       "url": "https://github.com/microsoft/quantum",
-      "branch": "feature/standalone",
+      "branch": "master",
       "branch_mapping": {}
     }
   ],