chore: migrate digicert signing action to Node.js 24 successor - BED-8168

digicert/ssm-code-signing has been deprecated by the upstream maintainer
and will not receive further updates, including a Node.js 24 runtime upgrade.
Per the maintainer's guidance, migrate to the successor action
digicert/code-signing-software-trust-action@v1.2.1, which runs on Node.js 24
and preserves the PKCS11_CONFIG output our sign job consumes.

Upstream notice: digicert/ssm-code-signing#60

Author: StranDutton

.github/workflows/publish.yml

@@ -98,7 +98,7 @@ jobs:
 
       - name: Install DigiCert Client Tools
         id: digicert
-        uses: digicert/ssm-code-signing@1d820463733701cf1484c7eb5d7d24a15ca2c454 # ratchet:digicert/ssm-code-signing@v1.2.1
+        uses: digicert/code-signing-software-trust-action@fae23a455ba4bde62b64fd7cb2f81ade788f5a95 # ratchet:digicert/code-signing-software-trust-action@v1.2.1
 
       - name: Set PKCS#11 Paths
         id: pkcs11