chore: Set version to 0.9.4-SNAPSHOT post-release (#436)

Author: kggilmer

gradle.properties

@@ -6,7 +6,7 @@ kotlin.native.ignoreDisabledTargets=true
 org.gradle.jvmargs=-Xmx6g -XX:MaxPermSize=6g -XX:MaxMetaspaceSize=1G
 
 # sdk
-sdkVersion=0.9.3-alpha
+sdkVersion=0.9.4-SNAPSHOT
 
 # codegen
 smithyVersion=1.13.1