chore: update Python setup step to specify version 3.14 for the publish and sign workflow (hiero-ledger#2162)

Signed-off-by: Ntege Daniel <danientege785@gmail.com>

Author: danielmarv

.github/workflows/publish.yml

@@ -66,6 +66,11 @@ jobs:
         with:
           egress-policy: audit
 
+      - name: Set up Python
+        uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
+        with:
+          python-version: '3.14'
+
       - name: Download distributions
         uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with: