Update build-single.template

.github/workflows/build-single.template

@@ -2,6 +2,10 @@ name: Build single
 on:
   workflow_dispatch:
     inputs:
+      sourcerepo:
+        description: Source repository
+        required: true
+        default: 'master'
       choice:
         type: choice
         description: Choose a board
@@ -30,7 +34,7 @@ jobs:
       runner: "big"
       part: 1
       of: 1
-      sourcerepo: 'master'
+      sourcerepo: '${{ github.event.inputs.sourcerepo }}'
       include: 'grep -w ${{ github.event.inputs.choice }} | '
       exclude: ''
       uploading: false