Add .xcf (gimp) file to lfs at default

Author: Thasan

src/GitHub.Api/Resources/.gitattributes

@@ -17,6 +17,7 @@
 *.iff filter=lfs diff=lfs merge=lfs -text
 *.pict filter=lfs diff=lfs merge=lfs -text
 *.dds filter=lfs diff=lfs merge=lfs -text
+*.xcf filter=lfs diff=lfs merge=lfs -text
 
 # Audio formats
 *.mp3 filter=lfs diff=lfs merge=lfs -text
@@ -63,4 +64,4 @@
 *.7z filter=lfs diff=lfs merge=lfs -text
 *.gz filter=lfs diff=lfs merge=lfs -text
 *.rar filter=lfs diff=lfs merge=lfs -text
-*.tar filter=lfs diff=lfs merge=lfs -text
+*.tar filter=lfs diff=lfs merge=lfs -text