Upgrade to Netty 4.1.91 and Checkstyle 10.9.3

Author: jhoeller

build.gradle

@@ -28,7 +28,7 @@ configure(allprojects) { project ->
 	dependencyManagement {
 		imports {
 			mavenBom "com.fasterxml.jackson:jackson-bom:2.12.7"
-			mavenBom "io.netty:netty-bom:4.1.90.Final"
+			mavenBom "io.netty:netty-bom:4.1.91.Final"
 			mavenBom "io.projectreactor:reactor-bom:2020.0.31"
 			mavenBom "io.r2dbc:r2dbc-bom:Arabba-SR13"
 			mavenBom "io.rsocket:rsocket-bom:1.1.3"
@@ -340,7 +340,7 @@ configure([rootProject] + javaProjects) { project ->
 	}
 
 	checkstyle {
-		toolVersion = "10.9.1"
+		toolVersion = "10.9.3"
 		configDirectory.set(rootProject.file("src/checkstyle"))
 	}