add typing_extensions for compatibility

requirements.txt

@@ -4,3 +4,4 @@ Pillow
 qreader
 opencv-python
 pyzbar
+typing_extensions  # PYTHON < 3.11: add types

setup.py

@@ -53,7 +53,9 @@ setup(
         'qrcode',
         'Pillow',
         'qreader',
-        'opencv-python'
+        'pyzbar',
+        'opencv-python',
+        'typing_extensions'  # PYTHON < 3.11: add types
     ],
 
     project_urls={

utils.py

@@ -13,6 +13,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+from __future__ import annotations  # for compatibility with Python < 3.11
 import csv
 import glob
 import io