Fix compose lint violations

Author: wenli-cai

workflow-trace-viewer/src/jvmMain/kotlin/com/squareup/workflow1/traceviewer/model/Node.kt

@@ -1,7 +1,5 @@
 package com.squareup.workflow1.traceviewer.model
 
-import com.squareup.moshi.Json
-
 /**
  * Since the logic of Workflow is hierarchical (where each workflow may have parent workflows and/or
  * children workflows, a tree structure is most appropriate for representing the data rather than

workflow-trace-viewer/src/jvmMain/kotlin/com/squareup/workflow1/traceviewer/ui/WorkflowTree.kt

@@ -17,7 +17,6 @@ import androidx.compose.runtime.mutableStateListOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
-import androidx.compose.runtime.snapshots.SnapshotStateList
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color