Remove unused variable in a test in RNGP

Summary:
Changelog:
[Internal] [Changed] - Remove unused variable in a test in RNGP

Created from CodeHub with https://fburl.com/edit-in-codehub

Reviewed By: cipolleschi

Differential Revision: D43185910

fbshipit-source-id: b1f328592e0b38654fd2e0a36304ce8f1d433b44

Author: cortinico

packages/react-native-gradle-plugin/src/test/kotlin/com/facebook/react/tasks/GenerateCodegenArtifactsTaskTest.kt

@@ -25,7 +25,6 @@ class GenerateCodegenArtifactsTaskTest {
 
   @Test
   fun generateCodegenSchema_inputFiles_areSetCorrectly() {
-    val codegenDir = tempFolder.newFolder("codegen")
     val outputDir = tempFolder.newFolder("output")
 
     val task = createTestTask<GenerateCodegenArtifactsTask> { it.generatedSrcDir.set(outputDir) }