Add explicit junit launcher dependency

Author: JordonPhillips

codegen/buildSrc/src/main/kotlin/smithy-python.java-conventions.gradle.kts

@@ -37,6 +37,7 @@ dependencies {
     testImplementation(platform(libs.junit.bom))
     testImplementation(libs.junit.jupiter.api)
     testRuntimeOnly(libs.junit.jupiter.engine)
+    testRuntimeOnly(libs.junit.platform.launcher)
     testImplementation(libs.junit.jupiter.params)
     compileOnly("com.github.spotbugs:spotbugs-annotations:${spotbugs.toolVersion.get()}")
     testCompileOnly("com.github.spotbugs:spotbugs-annotations:${spotbugs.toolVersion.get()}")

codegen/gradle/libs.versions.toml

@@ -20,6 +20,7 @@ junit-bom = { module = "org.junit:junit-bom", version.ref = "junit5" }
 junit-jupiter-api = { module = "org.junit.jupiter:junit-jupiter-api", version.ref = "junit5" }
 junit-jupiter-engine = { module = "org.junit.jupiter:junit-jupiter-engine", version.ref = "junit5" }
 junit-jupiter-params = { module = "org.junit.jupiter:junit-jupiter-params", version.ref = "junit5" }
+junit-platform-launcher = { module = "org.junit.platform:junit-platform-launcher" }
 
 # plugin artifacts for buildsrc plugins
 test-logger-plugin = { module = "com.adarshr:gradle-test-logger-plugin", version.ref = "test-logger-plugin" }