Remove Spring Integration version override

Closes gh-1322

Author: snicoll

samples/integration/pom.xml

@@ -17,7 +17,6 @@
 
 	<properties>
 		<java.version>11</java.version>
-		<spring-integration.version>5.5.7-SNAPSHOT</spring-integration.version>
 	</properties>
 
 	<dependencies>

spring-native-docs/src/main/asciidoc/support.adoc

@@ -217,4 +217,3 @@ NOTE: While building a project that contains Spring Cloud Config Client, it is n
 * Kotlin Coroutines are supported but currently require additional reflection entries due to how Coroutines generates bytecode with an `Object` return type.
 * Sealed class are not supported yet due to https://github.com/oracle/graal/issues/3870.
 * https://docs.spring.io/spring-data/commons/docs/current/reference/html/#repositories.custom-implementations[Custom repository] implementation fragments need to be annotated with `@Component`.
-* Spring Integration requires Spring Integration 5.5.7 or later.