Enable OpenSSF Scorecard Action and badge (#1382)

Closes #1379

Badge score on the badge will be probably be 5.5 (which is a good score).

.github/workflows/scorecard.yml

@@ -0,0 +1,57 @@
+# This workflow uses actions that are not certified by GitHub. They are provided
+# by a third-party and are governed by separate terms of service, privacy
+# policy, and support documentation.
+
+name: Scorecard supply-chain security
+on:
+  # For Branch-Protection check. Only the default branch is supported. See
+  # https://github.com/ossf/scorecard/blob/main/docs/checks.md#branch-protection
+  branch_protection_rule:
+  # To guarantee Maintained check is occasionally updated. See
+  # https://github.com/ossf/scorecard/blob/main/docs/checks.md#maintained
+  schedule:
+    - cron: '17 14 * * 1'
+  push:
+    branches: [ "master" ]
+
+# Declare default permissions as read only.
+permissions: read-all
+
+jobs:
+  analysis:
+    name: Scorecard analysis
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write # to upload the results to code-scanning dashboard
+      id-token: write # to publish results and get a badge (see publish_results below)
+
+    steps:
+      - name: "Checkout code"
+        uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8 # v3.1.0
+        with:
+          persist-credentials: false
+
+      - name: "Run analysis"
+        uses: ossf/scorecard-action@e38b1902ae4f44df626f11ba0734b14fb91f8f86 # v2.1.2
+        with:
+          results_file: results.sarif
+          results_format: sarif
+          #  Publish results to OpenSSF REST API for easy access by consumers and
+          #  allows the repository to include the Scorecard badge.
+          #  See https://github.com/ossf/scorecard-action#publishing-results.
+          publish_results: true
+
+      # Upload the results as artifacts (optional). Commenting out will disable uploads of run results in SARIF
+      # format to the repository Actions tab.
+      - name: "Upload artifact"
+        uses: actions/upload-artifact@3cea5372237819ed00197afe530f5a7ea3e805c8 # v3.1.0
+        with:
+          name: SARIF file
+          path: results.sarif
+          retention-days: 5
+
+      # Upload the results to GitHub's code scanning dashboard.
+      - name: "Upload to code-scanning"
+        uses: github/codeql-action/upload-sarif@17573ee1cc1b9d061760f3a006fc4aac4f944fd5 # v2.2.4
+        with:
+          sarif_file: results.sarif

README.md

@@ -1,5 +1,7 @@
 # window.fetch polyfill
 
+[![OpenSSF Scorecard](https://api.securityscorecards.dev/projects/github.com/JakeChampion/fetch/badge)](https://securityscorecards.dev/viewer/?uri=github.com/JakeChampion/fetch)
+
 The `fetch()` function is a Promise-based mechanism for programmatically making
 web requests in the browser. This project is a polyfill that implements a subset
 of the standard [Fetch specification][], enough to make `fetch` a viable