Update requirements-docker.txt

update UniMERNet to 0.2.1

requirements-docker.txt

@@ -8,7 +8,7 @@ fast-langdetect==0.2.0
 wordninja>=2.0.0
 scikit-learn>=1.0.2
 pdfminer.six==20231228
-unimernet==0.2.0
+unimernet==0.2.1
 matplotlib
 ultralytics
 paddleocr==2.7.3