Bump blinker from 1.7.0 to 1.8.1 in /backend/src

Bumps [blinker](https://github.com/pallets-eco/blinker) from 1.7.0 to 1.8.1.
- [Release notes](https://github.com/pallets-eco/blinker/releases)
- [Changelog](https://github.com/pallets-eco/blinker/blob/main/CHANGES.rst)
- [Commits](pallets-eco/blinker@1.7.0...1.8.1)

---
updated-dependencies:
- dependency-name: blinker
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

backend/src/requirements.txt

@@ -1,4 +1,4 @@
-blinker==1.7.0
+blinker==1.8.1
 click==8.1.7
 Flask==3.0.3
 itsdangerous==2.2.0