Added default branch for matrix job

.github/workflows/dashboard_matrix.yml

@@ -4,6 +4,11 @@ on:
   schedule:
     - cron: '0 12 * * *'  # Run every day at 12:00 UTC
   workflow_dispatch:
+  inputs:
+    branch:
+      description: "Branch to run tests on"
+      required: true
+      default: "reflow"
   push:
     branches:
       - reflow 
@@ -86,7 +91,7 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v2
         with:
-          ref: reflow
+          ref: ${{ github.event.inputs.branch }}
 
       - name: Download dependencies
         run: go get -v ./...