chore: require core v1.1.0

Bump the root module's core requirement from v1.0.0 to the freshly
released core/v1.1.0, which carries the breaking Executor change
(ExecuteTxs now returns ExecuteResult). The code has depended on this
API since #3282 but go.mod still required v1.0.0, building only via the
local `replace => ./core`. External consumers ignore that replace, so
this must be v1.1.0 for a working release.

Prerequisite for tagging v1.2.1 (v1.2.0 shipped with the stale v1.0.0
requirement and is superseded).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: tac0turtle

go.mod

@@ -17,7 +17,7 @@ require (
 	github.com/celestiaorg/go-square/v3 v3.0.2
 	github.com/celestiaorg/nmt v0.24.3
 	github.com/celestiaorg/utils v0.1.0
-	github.com/evstack/ev-node/core v1.0.0
+	github.com/evstack/ev-node/core v1.1.0
 	github.com/filecoin-project/go-jsonrpc v0.10.1
 	github.com/go-kit/kit v0.13.0
 	github.com/go-viper/mapstructure/v2 v2.5.0