update attest dep and send IA header

Author: conorsloan

dist/index.js

@@ -67,7 +67,7 @@
     ]
   },
   "dependencies": {
-    "@actions/attest": "^1.3.1",
+    "@actions/attest": "^1.4.0",
     "@actions/core": "^1.10.1",
     "@actions/exec": "^1.1.1",
     "@actions/github": "^6.0.0",

package-lock.json

@@ -128,7 +128,9 @@ async function generateAttestation(
     token: options.token,
     sigstore: 'github',
     // Always store the attestation using the GitHub Attestations API
-    skipWrite: false
+    skipWrite: false,
+    // Identify the attestation to our API as an Immutable Action
+    headers: { 'X-GitHub-Publish-Action': subjectName }
   })
 }