Fix "empty object" syntax

(follow-up to 9981bc2 / #48)

Author: tianon

update.sh/vars.groovy

@@ -13,25 +13,25 @@ def defaultRepoMeta = [
 	['bot-branch', true],
 ]
 def rawReposData = [
-	['buildpack-deps', []],
+	['buildpack-deps', [:]],
 	['busybox', [
 		'pipeline-script': 'update.sh/legacy-pipeline.groovy',
 		'env': 'BUSYBOX_VERSION',
 		'update-script': 'true', // TODO determine if more can/should be done here
 	]],
-	['cassandra', []],
-	['docker', []],
-	['drupal', []],
-	['gcc', []],
+	['cassandra', [:]],
+	['docker', [:]],
+	['drupal', [:]],
+	['gcc', [:]],
 	['ghost', [
 		'pipeline-script': 'update.sh/legacy-pipeline.groovy',
 		'env': 'GHOST_VERSION',
 		'otherEnvs': [
 			['ghost-cli', 'GHOST_CLI_VERSION'],
 		],
 	]],
-	['golang', []],
-	['haproxy', []],
+	['golang', [:]],
+	['haproxy', [:]],
 	['hello-world', [
 		'pipeline-script': 'update.sh/legacy-pipeline.groovy',
 		'update-script': 'true',
@@ -44,20 +44,20 @@ def rawReposData = [
 			['openssl', 'OPENSSL_VERSION'],
 		],
 	]],
-	['julia', []],
-	['memcached', []],
-	['mongo', []],
-	['mysql', []],
-	['openjdk', []],
-	['php', []],
-	['postgres', []],
-	['pypy', []],
-	['python', []],
-	['rabbitmq', []],
-	['redmine', []],
-	['ruby', []],
-	['tomcat', []],
-	['wordpress', []],
+	['julia', [:]],
+	['memcached', [:]],
+	['mongo', [:]],
+	['mysql', [:]],
+	['openjdk', [:]],
+	['php', [:]],
+	['postgres', [:]],
+	['pypy', [:]],
+	['python', [:]],
+	['rabbitmq', [:]],
+	['redmine', [:]],
+	['ruby', [:]],
+	['tomcat', [:]],
+	['wordpress', [:]],
 
 	// TODO it would be great to have one of these jobs per namespace ("mcr.microsoft.com/windows", "redhat", etc.)
 	['external-pins', [