fix: remove unnecessary cast

[mmoayyed]

The cast here is unnecessary, and in some cases can cause a ClassCastException particularly when the environment created is a different type (as is the case with Spring Cloud Bootstrap)

[mmoayyed]

Example failure:

java.lang.ClassCastException: class org.springframework.cloud.bootstrap.BootstrapApplicationListener$1 cannot be cast to class org.springframework.core.env.StandardEnvironment (org.springframework.cloud.bootstrap.BootstrapApplicationListener$1 and org.springframework.core.env.StandardEnvironment are in unnamed module of loader 'app')
	at org.springframework.cloud.stream.function.RoutingFunctionEnvironmentPostProcessor.postProcessEnvironment(RoutingFunctionEnvironmentPostProcessor.java:45)
	at org.springframework.boot.support.EnvironmentPostProcessorApplicationListener.onApplicationEnvironmentPreparedEvent(EnvironmentPostProcessorApplicationListener.java:135)
	at org.springframework.boot.support.EnvironmentPostProcessorApplicationListener.onApplicationEvent(EnvironmentPostProcessorApplicationListener.java:118)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:180)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:173)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:151)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:133)
	at org.springframework.boot.context.event.EventPublishingRunListener.multicastInitialEvent(EventPublishingRunListener.java:137)
	at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:82)
	at org.springframework.boot.SpringApplicationRunListeners.lambda$environmentPrepared$0(SpringApplicationRunListeners.java:66)
	at java.base/java.util.ImmutableCollections$List12.forEach(ImmutableCollections.java:681)
	at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:123)
	at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:117)
	at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:65)
	at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:355)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
	at org.springframework.boot.builder.SpringApplicationBuilder.run(SpringApplicationBuilder.java:154)
	at org.springframework.cloud.bootstrap.BootstrapApplicationListener.bootstrapServiceContext(BootstrapApplicationListener.java:198)
	at org.springframework.cloud.bootstrap.BootstrapApplicationListener.onApplicationEvent(BootstrapApplicationListener.java:114)
	at org.springframework.cloud.bootstrap.BootstrapApplicationListener.onApplicationEvent(BootstrapApplicationListener.java:77)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:180)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:173)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:151)
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:133)
	at org.springframework.boot.context.event.EventPublishingRunListener.multicastInitialEvent(EventPublishingRunListener.java:137)
	at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:82)
	at org.springframework.boot.SpringApplicationRunListeners.lambda$environmentPrepared$0(SpringApplicationRunListeners.java:66)
	at java.base/java.util.ImmutableCollections$List12.forEach(ImmutableCollections.java:681)
	at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:123)
	at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:117)
	at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:65)
	at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:355)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
	at org.springframework.boot.builder.SpringApplicationBuilder.run(SpringApplicationBuilder.java:154)