Use sharplispers for cl-png for now.

quicklisp · quicklisp · commit 0bf065cc9b03 · 2021-09-30T19:37:50.000-04:00
diff --git a/projects/cl-png/source.txt b/projects/cl-png/source.txt
@@ -1 +1 @@
-git https://github.com/ljosa/cl-png.git
+git https://github.com/sharplispers/cl-png.git

Original file line number	Diff line number	Diff line change
`@@ -1 +1 @@`
`1`		`-git https://github.com/ljosa/cl-png.git`
	`1`	`+git https://github.com/sharplispers/cl-png.git`