Add imgui 1.80 (#247)

packages/i/imgui/xmake.lua

@@ -6,6 +6,7 @@ package("imgui")
     add_urls("https://github.com/ocornut/imgui/archive/$(version).tar.gz",
              "https://github.com/ocornut/imgui.git")
 
+    add_versions("v1.80", "9da756d65d18a34cbb4f30ae64e6d6c42f94907b070ad3abaf553cb99e4ad403")
     add_versions("v1.79", "f1908501f6dc6db8a4d572c29259847f6f882684b10488d3a8d2da31744cd0a4")
     add_versions("v1.75", "1023227fae4cf9c8032f56afcaea8902e9bfaad6d9094d6e48fb8f3903c7b866")