By Pavel Polityuk KYIV (Reuters) – Ukraine urged its allies on Friday to send more weapons as its forces dug in to slow Russia’s military advance through the eastern Donbas region, while its chief negotiator said a turning part was approaching in the conflict. Signalling that the Kremlin was in no mood for compromise, President Vladimir Putin said continued use of sanctions against Russia for the invasion it launched in February risked causing “catastrophic” energy price rises. His top diplomat, Sergei Lavrov, clashed with his Western counterparts at a G20 meeting, where they urged Russia to a…