Bump requests from 2.23.0 to 2.31.0 in /backend

Bumps [requests](https://github.com/psf/requests) from 2.23.0 to 2.31.0.
- [Release notes](https://github.com/psf/requests/releases)
- [Changelog](https://github.com/psf/requests/blob/main/HISTORY.md)
- [Commits](psf/requests@v2.23.0...v2.31.0)

---
updated-dependencies:
- dependency-name: requests
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

backend/requirements-dev.txt

@@ -12,7 +12,7 @@ certifi==2023.7.22
     # via
     #   -r requirements.txt
     #   requests
-chardet==3.0.4
+charset-normalizer==3.2.0
     # via
     #   -r requirements.txt
     #   requests
@@ -106,7 +106,7 @@ python-dateutil==2.8.1
     #   matplotlib
 regex==2020.4.4
     # via black
-requests==2.23.0
+requests==2.31.0
     # via -r requirements.txt
 scipy==1.10.0
     # via

backend/requirements.txt

@@ -1,6 +1,6 @@
 certifi==2023.7.22
     # via requests
-chardet==3.0.4
+charset-normalizer==3.2.0
     # via requests
 click==7.1.1
     # via uvicorn
@@ -40,7 +40,7 @@ pyseagull==1.0.0b3
     # via -r requirements.in
 python-dateutil==2.8.1
     # via matplotlib
-requests==2.23.0
+requests==2.31.0
     # via -r requirements.in
 scipy==1.10.0
     # via pyseagull