Use JSON to parse Foreman API responses

The PSON parser is deprecated and Foreman doesn't actually send PSON; it
sends JSON.

See https://www.puppet.com/docs/puppet/8/http_api/pson.html

lib/puppet/functions/foreman/foreman.rb

@@ -87,7 +87,7 @@ def foreman(item, search, per_page = "20", foreman_url = "https://localhost", fo
         http.use_ssl = true if uri.scheme == 'https'
         http.verify_mode = OpenSSL::SSL::VERIFY_NONE if http.use_ssl?
       end
-      results = Timeout::timeout(timeout) { PSON.parse http.request(req).body }
+      results = Timeout::timeout(timeout) { JSON.parse http.request(req).body }
     rescue Exception => e
       raise Puppet::ParseError, "Failed to contact Foreman at #{foreman_url}: #{e}"
     end

lib/puppet/functions/foreman/smartvar.rb

@@ -31,7 +31,7 @@ def smartvar(var, foreman_url = "http://foreman", foreman_user = "admin", forema
     req['Accept'] = 'application/json'
 
     begin
-      Timeout::timeout(5) { PSON.parse(http.request(req).body)["value"] }
+      Timeout::timeout(5) { JSON.parse(http.request(req).body)["value"] }
     rescue Exception => e
       raise Puppet::ParseError, "Failed to contact Foreman #{e}"
     end