Bump Django to latest secure 4.2.x version (#14962)

See https://www.djangoproject.com/weblog/2024/aug/06/security-releases/

requirements/dev.txt

@@ -451,9 +451,9 @@ dj-database-url==2.2.0 \
     --hash=sha256:3e792567b0aa9a4884860af05fe2aa4968071ad351e033b6db632f97ac6db9de \
     --hash=sha256:9f9b05058ddf888f1e6f840048b8d705ff9395e3b52a07165daa3d8b9360551b
     # via -r requirements/prod.txt
-django==4.2.14 \
-    --hash=sha256:3ec32bc2c616ab02834b9cac93143a7dc1cdcd5b822d78ac95fc20a38c534240 \
-    --hash=sha256:fc6919875a6226c7ffcae1a7d51e0f2ceaf6f160393180818f6c95f51b1e7b96
+django==4.2.15 \
+    --hash=sha256:61ee4a130efb8c451ef3467c67ca99fdce400fedd768634efc86a68c18d80d30 \
+    --hash=sha256:c77f926b81129493961e19c0e02188f8d07c112a1162df69bfab178ae447f94a
     # via
     #   -r requirements/prod.txt
     #   dj-database-url

requirements/prod.in

@@ -22,7 +22,7 @@ django-memoize==2.3.1
 django-mozilla-product-details==1.0.3
 django-storages[google]==1.14.4
 django-watchman==1.3.0
-Django==4.2.14
+Django==4.2.15
 django-rq==2.10.2
 docutils==0.21.2
 envcat==0.1.1

requirements/prod.txt

@@ -298,9 +298,9 @@ dj-database-url==2.2.0 \
     --hash=sha256:3e792567b0aa9a4884860af05fe2aa4968071ad351e033b6db632f97ac6db9de \
     --hash=sha256:9f9b05058ddf888f1e6f840048b8d705ff9395e3b52a07165daa3d8b9360551b
     # via -r requirements/prod.in
-django==4.2.14 \
-    --hash=sha256:3ec32bc2c616ab02834b9cac93143a7dc1cdcd5b822d78ac95fc20a38c534240 \
-    --hash=sha256:fc6919875a6226c7ffcae1a7d51e0f2ceaf6f160393180818f6c95f51b1e7b96
+django==4.2.15 \
+    --hash=sha256:61ee4a130efb8c451ef3467c67ca99fdce400fedd768634efc86a68c18d80d30 \
+    --hash=sha256:c77f926b81129493961e19c0e02188f8d07c112a1162df69bfab178ae447f94a
     # via
     #   -r requirements/prod.in
     #   dj-database-url