Mention limit in error message

Author: radarhere

src/PIL/PngImagePlugin.py

@@ -140,7 +140,7 @@ def _safe_zlib_decompress(s: bytes) -> bytes:
     dobj = zlib.decompressobj()
     plaintext = dobj.decompress(s, MAX_TEXT_CHUNK)
     if dobj.unconsumed_tail:
-        msg = "Decompressed Data Too Large"
+        msg = "Decompressed data too large for PngImagePlugin.MAX_TEXT_CHUNK"
         raise ValueError(msg)
     return plaintext