Rename tag parameter to label

Remove this error message that pops up when validation the code:
puppet-syntax: tag is a metaparam; this value will inherit to all contained resources

manifests/image.pp

@@ -4,15 +4,15 @@
 # @param image
 #   TODO: add documentation
 #
-# @param tag
+# @param label
 #  TODO: add documentation
 #
 define docker::image (
   Enum['present', 'absent'] $ensure = 'present',
   String[1]                 $image  = $name,
-  String[1]                 $tag    = 'latest', # TODO tag is a metaparameter and needs to get renamed
+  String[1]                 $label  = 'latest',
 ) {
-  $image_real = "${image}:${tag}"
+  $image_real = "${image}:${label}"
   $image_cond = "images=`docker images | grep \"${image}\" | awk 'BEGIN{ OFS=\":\" } { print \$1, \$2 }'` && exist='false' && for img in \${images} ; do if [ \${img} == \"${image_real}\" ]; then exist='true' ; fi ; done && test \${exist} == 'true'" #lint:ignore:140chars
 
   if $ensure == 'present' {

spec/defines/image_spec.rb

@@ -61,8 +61,8 @@
         end
       end
 
-      context 'with tag set to valid value' do
-        let(:params) { { tag: '2.4.2' } }
+      context 'with label set to valid value' do
+        let(:params) { { label: '2.4.2' } }
 
         it { is_expected.to contain_exec('docker_image_test-title_pull').with_command('docker pull test-title:2.4.2') }
       end