CI: upload the .snyk policy file in the [kosli attest snyk] command

sh/kosli.sh

@@ -65,6 +65,7 @@ kosli_attest_snyk()
     --artifact-type=docker \
     --host="${hostname}" \
     --api-token="${api_token}" \
+    --attachments="$(repo_root)/.snyk" \
     --name=exercises-start-points.snyk-scan \
     --scan-results="$(repo_root)/snyk.json"
 }