fix: Use same env as in beam (#50)

Use same env as in beam

Author: nahsi

flux/apps/lightmare/lightmare/app/base/release.yml

@@ -31,4 +31,4 @@ spec:
           memory: 2.48 gib
         chainAdapter:
           ipfsGatewayEndpoint: https://ipfs-gateway.fluence.dev
-          privateRPCTokenSecretRef: ${PRIVATE_RPC_TOKEN:=null}
+          privateRPCTokenSecretRef: ${PRIVATE_RPC_SECRET_REF:=null}