chore: reduce Dependabot noise with weekly schedule and production-only updates (#1079)

This change reduces the noise from Dependabot PRs by making two
adjustments:

1. Switching from daily to weekly update checks, which significantly
reduces the number of PRs while still keeping dependencies reasonably
up-to-date.

2. Limiting updates to production dependencies only, excluding
devDependencies which are less critical for security and stability. We
still have the projen updates that run more often. Dependabot was always
just intended as a fallback.

---
By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache-2.0 license

Author: mrgrain

.github/dependabot.yml

@@ -1673,8 +1673,11 @@ new pj.YamlFile(repo, '.github/dependabot.yml', {
     updates: [
       {
         'package-ecosystem': 'npm',
-        'schedule': { interval: 'daily' },
+        'schedule': { interval: 'weekly' },
         'labels': ['auto-approve'],
+        'allow': [{
+          'dependency-type': 'production',
+        }],
         'directories': ['/', ...repoProject.node.children
           .filter(child => child instanceof TypeScriptWorkspace)
           .map(ts => `/${path.relative(repoProject.outdir, ts.outdir)}`)