Attempt to work around inputs on a scheduled workflow run

.github/workflows/update-build-time-diagrams.yml

@@ -5,6 +5,7 @@ on:
     # At 23:00
     # See https://docs.github.com/en/actions/reference/events-that-trigger-workflows#schedule
     - cron: "0 23 * * *"
+    - cron: "20 11 * * *"
 
   workflow_dispatch:
     inputs:
@@ -69,18 +70,21 @@ jobs:
 
       - name: "Update build stats and re-generate diagrams"
         shell: bash -e {0}
+        env:
+          get_stats: ${{ github.event_name == 'schedule' && true || github.event.inputs.get_stats }}
+          create_diagrams: ${{ github.event_name == 'schedule' && true || github.event.inputs.create_diagrams }} 
         run: |
-          if ${{ inputs.get_stats }}; then
+          if ${{ env.get_stats }}; then
             main/build-stats/get-build-stats.py | tee -a gh-pages/build-stats.csv
             git -C gh-pages add build-stats.csv
           fi
-          if ${{ inputs.create_diagrams }}; then
+          if ${{ env.create_diagrams }}; then
             main/build-stats/create-diagrams.py --datafile gh-pages/build-stats.csv
             mv index.html gh-pages/index.html
             mv fig-*.html gh-pages/
             git -C gh-pages add index.html fig-*.html
           fi
-          if [[ ${{ inputs.get_stats }} || ${{ inputs.create_diagrams }} ]]; then
+          if [[ ${{ env.get_stats }} || ${{ env.create_diagrams }} ]]; then
             cd gh-pages
             git commit -m "Automatically update stats build stats"
             git push origin HEAD:gh-pages