Russian state gas giant PAO Gazprom has secured a €2 billion ($2.17 billion) loan from Bank of China Ltd., the largest single-bank credit in the Russian company’s history and a sign of how Western sanctions are increasing Russia’s economic reliance on China. The deal, announced Thursday by Gazprom, is the latest in expanding Chinese investment in Russia’s oil and gas sector, the country’s main export earner that has been hamstrung by U.S. sanctions barring long-term dollar lending to some Russian firms. Gazprom…