ci: use env vars for central auth

Author: javorosas

.github/workflows/publish.yml

@@ -23,8 +23,11 @@ jobs:
           java-version: 25
           cache: maven
           server-id: central
-          server-username: ${{ secrets.CENTRAL_TOKEN_USERNAME }}
-          server-password: ${{ secrets.CENTRAL_TOKEN_PASSWORD }}
+          server-username: CENTRAL_TOKEN_USERNAME
+          server-password: CENTRAL_TOKEN_PASSWORD
+        env:
+          CENTRAL_TOKEN_USERNAME: ${{ secrets.CENTRAL_TOKEN_USERNAME }}
+          CENTRAL_TOKEN_PASSWORD: ${{ secrets.CENTRAL_TOKEN_PASSWORD }}
 
       - name: Check release gate
         id: gate