chore(deps)(deps): bump spacy from 3.8.2 to 3.8.7 in /backend

Bumps [spacy](https://github.com/explosion/spaCy) from 3.8.2 to 3.8.7.
- [Release notes](https://github.com/explosion/spaCy/releases)
- [Commits](explosion/spaCy@release-v3.8.2...release-v3.8.7)

---
updated-dependencies:
- dependency-name: spacy
  dependency-version: 3.8.7
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

backend/requirements.txt

@@ -5,7 +5,7 @@ pydantic==2.11.9
 python-dotenv==1.1.1
 
 # Enhanced content analysis dependencies
-spacy==3.8.2
+spacy==3.8.7
 nltk==3.9.1
 textblob==0.18.0
 scikit-learn==1.5.2