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

@@ -18,7 +18,7 @@ coreapi==2.3.3
 coreschema==0.0.4
 cycler==0.12.1
 decorator==5.1.1
-Django==4.1.13
+Django==4.2.15
 django-bootstrap4==3.0.1
 django-extensions==3.1.3
 django-filter==2.4.0