chore: update actions/checkout from v4 to v6 in setup-iceberg and setup-spark builders (#2857)

Author: bjornjorgensen

.github/actions/setup-iceberg-builder/action.yaml

@@ -25,7 +25,7 @@ runs:
   using: "composite"
   steps:
     - name: Clone Iceberg repo
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
       with:
         repository: apache/iceberg
         path: apache-iceberg

.github/actions/setup-iceberg-rust-builder/action.yaml

@@ -25,7 +25,7 @@ runs:
   using: "composite"
   steps:
     - name: Clone Iceberg repo
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
       with:
         repository: apache/iceberg
         path: apache-iceberg

.github/actions/setup-spark-builder/action.yaml

@@ -28,7 +28,7 @@ runs:
   using: "composite"
   steps:
     - name: Clone Spark repo
-      uses: actions/checkout@v4
+      uses: actions/checkout@v6
       with:
         repository: apache/spark
         path: apache-spark