validmeasures/ppitables: ppitables v0.5.2

This is the seventh CRAN release of ppitables. In this release, I added: new PPI tables for Rwanda using the new PPI calculation approach developed by the International Poverty Alliance (IPA) based on data from Rwanda's 2016/2017 Integrated Household Living Conditions Survey (EICV5) produced by the National Institute of Statistics Rwanda (NISR) and the Ministry of Finance and Economic Planning updated steer data that serves as an index to the tables to include the new Rwanda PPI tables