Fix dependency caching in CI workflow

Signed-off-by: Aravindhan Ayyanathan <aravindhan.a@est.tech>

Author: aravindtga

.github/workflows/ci.yaml

@@ -1,3 +1,17 @@
+# Copyright 2026 The kpt Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
 name: CI
 
 on:
@@ -35,5 +49,6 @@ jobs:
       with:
         go-version-file: go/fn/go.mod
         install-kpt: 'false'
+        cache-dependency-path: go/**/go.sum
     - name: Build, Test, Lint
       run: hack/ci-validate-go.sh