Fix type annotation for older Python versions

src/dymoprint/labeler.py

@@ -6,7 +6,7 @@
 # this notice are preserved.
 # === END LICENSE STATEMENT ===
 import array
-from typing import Optional
+from typing import List, Optional
 
 import usb
 
@@ -48,7 +48,7 @@ def __init__(self, devout, devin, synwait=None, tape_size_mm=12):
         """Initialize the LabelManager object. (HLF)"""
 
         self.tape_size_mm = tape_size_mm
-        self.cmd: list[int] = []
+        self.cmd: List[int] = []
         self.response = False
         self.bytesPerLine_ = None
         self.dotTab_ = 0
@@ -203,7 +203,7 @@ def getStatus(self):
         response = self.sendCommand()
         print(response)
 
-    def printLabel(self, lines: list[list[int]], margin_px=DEFAULT_MARGIN_PX):
+    def printLabel(self, lines: List[List[int]], margin_px=DEFAULT_MARGIN_PX):
         """Print the label described by lines. (Automatically split label if
         larger than maxLines)"""
 
@@ -212,7 +212,7 @@ def printLabel(self, lines: list[list[int]], margin_px=DEFAULT_MARGIN_PX):
             del lines[0 : self.maxLines]
         self.rawPrintLabel(lines, margin_px=margin_px)
 
-    def rawPrintLabel(self, lines: list[list[int]], margin_px=DEFAULT_MARGIN_PX):
+    def rawPrintLabel(self, lines: List[List[int]], margin_px=DEFAULT_MARGIN_PX):
         """Print the label described by lines. (HLF)"""
 
         # optimize the matrix for the dymo label printer