chore(nexus): Use env creds for close/promote

Author: PLNech

build.gradle

@@ -54,6 +54,8 @@ apply plugin: 'io.codearte.nexus-staging'
 
 nexusStaging {
     packageGroup = PUBLISH_GROUP_ID
+    username = System.getenv("NEXUS_USERNAME")
+    password = System.getenv("NEXUS_PASSWORD")
     stagingProfileId = 'f6edc053ff913'
     numberOfRetries = 3
     delayBetweenRetriesInMillis = 3000