Update MANIFEST.in

Author: hsz1273327

MANIFEST.in

@@ -3,7 +3,7 @@ include README.md
 include CHANGELOG.md
 include requirements.txt
 include postgresql_kernel/kernel.json
-recursive-include postgresql_kernel *.pyx *.pxd *.pxi *.py *.c *.h *.temp *.jinja
+recursive-include postgresql_kernel *.pyx *.pxd *.pxi *.py *.c *.h *.temp *.jinja *.png
 prune .git
 prune docs/build
 prune dist