Update io.projectreactor to 2020.0.20

Closes gh-11414

buildSrc/build.gradle

@@ -80,7 +80,7 @@ dependencies {
 	implementation localGroovy()
 
 	implementation 'io.github.gradle-nexus:publish-plugin:1.1.0'
-	implementation 'io.projectreactor:reactor-core:3.4.18'
+	implementation 'io.projectreactor:reactor-core:3.4.19'
 	implementation 'gradle.plugin.org.gretty:gretty:3.0.1'
 	implementation 'com.apollographql.apollo:apollo-runtime:2.4.5'
 	implementation 'com.github.ben-manes:gradle-versions-plugin:0.38.0'

dependencies/spring-security-dependencies.gradle

@@ -8,7 +8,7 @@ javaPlatform {
 
 dependencies {
 	api platform("org.springframework:spring-framework-bom:$springFrameworkVersion")
-	api platform("io.projectreactor:reactor-bom:2020.0.19")
+	api platform("io.projectreactor:reactor-bom:2020.0.20")
 	api platform("io.rsocket:rsocket-bom:1.1.2")
 	api platform("org.junit:junit-bom:5.8.2")
 	api platform("org.springframework.data:spring-data-bom:2021.1.4")