gears.surface: Update required lgi version

Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/gears/surface.lua.in

@@ -9,8 +9,10 @@ local type = type
 local capi = { awesome = awesome }
 local cairo = require("lgi").cairo
 
+-- This checks for '<= 0.5' because there are git versions after 0.6 which still
+-- identify themselves as 0.6 but already have the needed cairo support
 if tonumber(string.match(require('lgi.version'), '(%d%.%d)')) <= 0.5 then
-    error("lgi too old, need at least version 0.7 (not yet released?) or recent git")
+    error("lgi too old, need at least version 0.6.1")
 end
 
 -- gears.surface