fix: requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-DJANGO-7642790
- https://snyk.io/vuln/SNYK-PYTHON-DJANGO-7642791
- https://snyk.io/vuln/SNYK-PYTHON-DJANGO-7642813
- https://snyk.io/vuln/SNYK-PYTHON-DJANGO-7642814

requirements.txt

@@ -9,7 +9,7 @@ types-bleach>=6
 celery>=5.2.6
 coverage>=4.5.4,<5.0    # Coverage 5.x moves from a json database to SQLite.  Moving to 5.x will require substantial rewrites in ietf.utils.test_runner and ietf.release.views
 defusedxml>=0.7.1    # for TastyPie when using xml; not a declared dependency
-Django>4.2,<5
+Django>4.2.15
 django-analytical>=3.1.0
 django-bootstrap5>=21.3
 django-celery-beat>=2.3.0