Use declare_resource for local package install

Per this comment:

chef/chef#3487 (comment)

We should not use the `provider` property of resources. We should
instead use the DSL method, #declare_resource. This commit converts the
definition to use that method.

README.md

@@ -16,6 +16,8 @@ cookbook doesn't support installing from networked package managers
 
 ## Requirements
 
+Chef 11.10.0+ for `declare_resource`.
+
 ### Platforms
 
 This cookbook uses Test Kitchen to do cross-platform convergence and

definitions/splunk_installer.rb

@@ -51,16 +51,14 @@
     end
   end
 
-  package params[:name] do
+  local_package_resource = case node['platform_family']
+                           when 'rhel'   then :rpm_package
+                           when 'debian' then :dpkg_package
+                           when 'omnios' then :solaris_package
+                           end
+
+  declare_resource local_package_resource, params[:name] do
     source cached_package.gsub(/\.Z/, '')
-    case node['platform_family']
-    when 'rhel'
-      provider Chef::Provider::Package::Rpm
-    when 'debian'
-      provider Chef::Provider::Package::Dpkg
-    when 'omnios'
-      provider Chef::Provider::Package::Solaris
-      options pkgopts.join(' ')
-    end
+    options pkgopts.join(' ') if platform?('omnios')
   end
 end