Update the version specification for the LD Server SDK.

Author: kinyoklion

build.gradle

@@ -97,7 +97,7 @@ dependencies {
     // This dependency is used internally, and not exposed to consumers on their own compile classpath.
     implementation 'com.google.guava:guava:23.0'
 
-    implementation group: 'com.launchdarkly', name: 'launchdarkly-java-server-sdk', version: '6.+'
+    implementation group: 'com.launchdarkly', name: 'launchdarkly-java-server-sdk', version: '[6.0.0, 7.0.0)'
     implementation 'dev.openfeature:sdk:[1.2.0,2.0.0)'
 
     // Use JUnit test framework