Add OpenSSF scorecard action (TraceMachina#486)

Ensure that we follow security best practices.

.github/workflows/scorecard.yaml

@@ -0,0 +1,47 @@
+---
+name: Scorecard supply-chain security
+on:
+  schedule:
+    # Non-peak hour 23:15 on Tuesdays.
+    - cron: '15 23 * * 1'
+  push:
+    branches: [ "main" ]
+
+permissions: read-all
+
+jobs:
+  analysis:
+    name: Scorecard analysis
+    runs-on: ubuntu-22.04
+    permissions:
+      security-events: write
+      id-token: write
+
+    steps:
+      - name: Checkout
+        uses: >- # v4.1.1
+          actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11
+        with:
+          persist-credentials: false
+
+      - name: Run analysis
+        uses: >- # v2.3.1
+          ossf/scorecard-action@0864cf19026789058feabb7e87baa5f140aac736
+        with:
+          results_file: results.sarif
+          results_format: sarif
+          publish_results: true
+
+      - name: Upload artifact
+        uses: >- # v4.0.0
+          actions/upload-artifact@c7d193f32edcb7bfad88892161225aeda64e9392
+        with:
+          name: SARIF file
+          path: results.sarif
+          retention-days: 5
+
+      - name: Upload to code-scanning
+        uses: >- # v3.22.11
+          github/codeql-action/upload-sarif@b374143c1149a9115d881581d29b8390bbcbb59c
+        with:
+          sarif_file: results.sarif