By Jeff Mason WASHINGTON (Reuters) -Group of Seven (G7) leaders including U.S. President Joe Biden will hold a video call on Sunday with Ukrainian President Volodymyr Zelenskiy in a show of unity the day before Russia marks its Victory Day holiday, the White House said. Talks will focus on the latest developments in Russia’s invasion of Ukraine, efforts to bolster the country and ways to demonstrate “continued G7 unity in our collective response, including by imposing severe costs for Putin’s war,” a spokesperson for the White House’s National Security Council said on Monday. The leaders of th…