By Susan Mathew and Anisha Sircar (Reuters) – European shares gained on Monday with tech stocks rallying more than 2%, while investors kept an eye out for more Western sanctions after Ukraine accused Russia of war crimes. The pan-European STOXX 600 index firmed 0.8%, with tech stocks jumping 2.1%, tracking gains in Wall Street’s Nasdaq after Elon Musk revealed a 9.2% stake in Twitter Inc. [.N] The sector also got a boost as Delivery Hero surged 10.7% after it launched a debt financing syndication equal to 1.4 billion euros ($1.55 billion) with proceeds to be used to bolster its liquidity posit…