Switch to oxipng.

Author: bobbens

.pre-commit-config.yaml

@@ -25,10 +25,9 @@ repos:
       args: ["--ignore-words", ".codespellignore" ]
       additional_dependencies:
         - tomli
-- repo: local
+- repo: https://github.com/shssoichiro/oxipng
+  rev: v9.1.5
   hooks:
-    - id: optipng
-      name: PNG Optimizer
-      entry: optipng
+    - id: oxipng
+      args: ["-o", "max", "--strip", "safe", "--alpha"]
       types: [png]
-      language: system