chore(meta): tweak update-meta workflow

Run once a day only, and pass in cache flag to keep download totals
accurate over time.

.github/workflows/update-metadata.yml

@@ -3,7 +3,7 @@ name: Update Metadata
 concurrency: jimeh/emacs-builds/update-metadata
 on:
   schedule:
-    - cron: "0 0,12 * * *"
+    - cron: "0 0 * * *"
   workflow_dispatch:
 
 jobs:
@@ -19,7 +19,9 @@ jobs:
           go-version: "1.21"
       - name: update total downloads shield JSON
         run: >-
-          go run . badges downloads -o total-downloads/shield.json
+          go run . badges downloads
+          --output total-downloads/shield.json
+          --cache total-downloads/.cache.json
         env:
           GITHUB_TOKEN: ${{ github.token }}
       - name: commit and push changes to meta branch