chore: run TIOBE weekly (#176)

We've been asked to [run the TIOBE workflow
weekly](https://discourse.canonical.com/t/tiobe-tics-news-maas-ui-go-1-24-ci-integration-tics-gh-self-hosted-runner/6038?u=tony-meyer).
This changes from monthly on the first of the month to weekly on
Sundays.

Author: tonyandrewmeyer

.github/workflows/tiobe.yaml

@@ -3,7 +3,7 @@ name: TIOBE
 on:
   workflow_dispatch:
   schedule:
-    - cron:  '0 7 1 * *'
+    - cron:  '0 7 * * 0'
 
 permissions: {}