Bump pypdf from 6.1.3 to 6.4.0 in /app/backend

Bumps [pypdf](https://github.com/py-pdf/pypdf) from 6.1.3 to 6.4.0.
- [Release notes](https://github.com/py-pdf/pypdf/releases)
- [Changelog](https://github.com/py-pdf/pypdf/blob/main/CHANGELOG.md)
- [Commits](py-pdf/pypdf@6.1.3...6.4.0)

---
updated-dependencies:
- dependency-name: pypdf
  dependency-version: 6.4.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

app/backend/requirements.txt

@@ -20,8 +20,6 @@ anyio==4.4.0
     #   openai
 asgiref==3.10.0
     # via opentelemetry-instrumentation-asgi
-async-timeout==5.0.1
-    # via aiohttp
 attrs==25.3.0
     # via aiohttp
 azure-ai-documentintelligence==1.0.2
@@ -47,8 +45,6 @@ azure-core-tracing-opentelemetry==1.0.0b11
     # via azure-monitor-opentelemetry
 azure-cosmos==4.9.0
     # via -r requirements.in
-azure-functions==1.24.0
-    # via -r requirements.in
 azure-identity==1.17.1
     # via
     #   -r requirements.in
@@ -97,11 +93,6 @@ cryptography==44.0.1
     #   pyjwt
 distro==1.9.0
     # via openai
-exceptiongroup==1.3.0
-    # via
-    #   anyio
-    #   hypercorn
-    #   taskgroup
 fixedint==0.1.6
     # via azure-monitor-opentelemetry-exporter
 flask==3.1.2
@@ -124,7 +115,7 @@ hpack==4.1.0
     # via h2
 httpcore==1.0.9
     # via httpx
-httpx==0.28.1
+httpx[http2]==0.28.1
     # via
     #   microsoft-kiota-http
     #   msgraph-core
@@ -343,13 +334,13 @@ pydantic-core==2.41.4
     # via pydantic
 pygments==2.19.2
     # via rich
-pyjwt==2.10.1
+pyjwt[crypto]==2.10.1
     # via
     #   -r requirements.in
     #   msal
 pymupdf==1.26.0
     # via -r requirements.in
-pypdf==6.1.3
+pypdf==6.4.0
     # via -r requirements.in
 python-dotenv==1.1.1
     # via
@@ -388,14 +379,10 @@ soupsieve==2.7
     # via beautifulsoup4
 std-uritemplate==2.0.5
     # via microsoft-kiota-abstractions
-taskgroup==0.2.2
-    # via hypercorn
 tenacity==9.1.2
     # via -r requirements.in
 tiktoken==0.12.0
     # via -r requirements.in
-tomli==2.2.1
-    # via hypercorn
 tqdm==4.66.5
     # via openai
 types-beautifulsoup4==4.12.0.20240511
@@ -407,29 +394,20 @@ types-pillow==10.2.0.20240822
 typing-extensions==4.15.0
     # via
     #   -r requirements.in
-    #   aiosignal
-    #   anyio
-    #   asgiref
     #   azure-ai-documentintelligence
     #   azure-core
     #   azure-cosmos
     #   azure-identity
     #   azure-search-documents
     #   azure-storage-blob
     #   azure-storage-file-datalake
-    #   exceptiongroup
-    #   hypercorn
-    #   multidict
     #   openai
     #   opentelemetry-api
     #   opentelemetry-sdk
     #   opentelemetry-semantic-conventions
     #   pydantic
     #   pydantic-core
-    #   pypdf
-    #   taskgroup
     #   typing-inspection
-    #   uvicorn
 typing-inspection==0.4.2
     # via pydantic
 urllib3==2.5.0
@@ -438,7 +416,6 @@ uvicorn==0.30.6
     # via -r requirements.in
 werkzeug==3.1.3
     # via
-    #   azure-functions
     #   flask
     #   quart
 wrapt==1.16.0
@@ -453,4 +430,4 @@ wsproto==1.2.0
 yarl==1.17.2
     # via aiohttp
 zipp==3.21.0
-    # via importlib-metadata
+    # via importlib-metadata