chore(ci): add OpenSSF scorecard

Author: scop

.github/workflows/scorecard.yaml

@@ -0,0 +1,21 @@
+name: Scorecard
+on:
+  branch_protection_rule:
+  schedule:
+    - cron: "42 4 * * MON"
+  push:
+    branches:
+      - main
+
+permissions: {}
+
+jobs:
+  scorecard:
+    name: Scorecard
+    permissions:
+      contents: read
+      id-token: write
+      security-events: write
+    uses: UpCloudLtd/workflows/.github/workflows/openssf-scorecard.yaml@main
+    with:
+      publish-results: true

README.md

@@ -1,5 +1,7 @@
 # UpCloud WHMCS Module
 
+[![OpenSSF Scorecard](https://api.scorecard.dev/projects/github.com/UpCloudLtd/upcloud-whmcs-module/badge)](https://scorecard.dev/viewer/?uri=github.com%2FUpCloudLtd%2Fupcloud-whmcs-module)
+
 This is the official WHMCS provisioning module for [UpCloud](https://upcloud.com/), allowing you to offer and manage UpCloud VPS services through your WHMCS installation.
 
 ## Features