chore(renovate): run github-actions updates monthly in renovate config 🗓️ (#95)

- switch schedule from weekly (on monday) to monthly (1st of month, `* 0-3 1 * *`)
- keep 14-day minimumReleaseAge

Author: glokos

.github/renovate.json5

@@ -8,15 +8,15 @@
   semanticCommits: "enabled",
   semanticCommitType: "deps",
   packageRules: [
-    // GitHub Actions updates: run weekly, skip releases newer than 2 weeks
+    // GitHub Actions updates: run monthly, skip releases newer than 2 weeks
     // to avoid picking up freshly published versions that may be unstable or
     // compromised, and pin to full commit SHAs (with the version as a
     // trailing comment) rather than mutable tags.
     // When both major and minor releases exist, propose only the latest bump
     // (typically major) instead of a separate minor PR.
     {
       matchManagers: ["github-actions"],
-      schedule: ["on monday"],
+      schedule: ["* 0-3 1 * *"],
       minimumReleaseAge: "14 days",
       // Track upgrades by semver tag, but pin the resolved version to its full
       // commit SHA (semver tag kept as a trailing comment). Use the coerced