Bump pypdf from 6.1.3 to 6.4.0 in /backend (#705)

dependabot[bot] · web-flow · commit 803e8a83884e · 2025-12-01T08:09:22.000+01:00
diff --git a/backend/requirements.txt b/backend/requirements.txt
@@ -8,4 +8,4 @@ openpyxl==3.1.5
 grequests==0.7.0
 pyclustering==0.10.1.2
 polyline==2.0.3
-pypdf==6.1.3
+pypdf==6.4.0
