Fix datamatrix 64x64 generation

Correcting dcol and crow values for 64x64 datamatrix.

render_barcode_datamatrix.py

@@ -74,7 +74,7 @@ SYMBOLS = {
     'sq44': (44, 44, 20, 20, 2, 2, 144, 56, 1),
     'sq48': (48, 48, 22, 22, 2, 2, 174, 68, 1),
     'sq52': (52, 52, 24, 24, 2, 2, 102, 42, 2),
-    'sq64': (64, 64, 16, 16, 4, 4, 140, 56, 2),
+    'sq64': (64, 64, 14, 14, 4, 4, 140, 56, 2),
     'sq72': (72, 72, 16, 16, 4, 4, 92, 36, 4),
     'sq80': (80, 80, 18, 18, 4, 4, 114, 48, 4),
     'sq88': (88, 88, 20, 20, 4, 4, 144, 56, 4),