Add FOSSA scanning workflow (open-telemetry#3279)

Co-authored-by: otelbot <197425009+otelbot@users.noreply.github.com>

Author: opentelemetrybot

.github/workflows/fossa.yml

@@ -0,0 +1,20 @@
+name: FOSSA scanning
+
+on:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+  fossa:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+
+      - uses: fossas/fossa-action@93a52ecf7c3ac7eb40f5de77fd69b1a19524de94 # v1.5.0
+        with:
+          api-key: ${{secrets.FOSSA_API_KEY}}
+          team: OpenTelemetry