Bump djangorestframework from 3.15.1 to 3.15.2

Bumps [djangorestframework](https://github.com/encode/django-rest-framework) from 3.15.1 to 3.15.2.
- [Release notes](https://github.com/encode/django-rest-framework/releases)
- [Commits](encode/django-rest-framework@3.15.1...3.15.2)

---
updated-dependencies:
- dependency-name: djangorestframework
  dependency-type: direct:production
...

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

requirements.txt

@@ -300,9 +300,9 @@ django-storages==1.14.2 \
 django-stronghold==0.4.0 \
     --hash=sha256:4127d5f9c11f6582a1c03e7758256b1fe5c872f64f212980e5ad5c67f5eeaa3d
     # via -r requirements.in
-djangorestframework==3.15.1 \
-    --hash=sha256:3ccc0475bce968608cf30d07fb17d8e52d1d7fc8bfe779c905463200750cbca6 \
-    --hash=sha256:f88fad74183dfc7144b2756d0d2ac716ea5b4c7c9840995ac3bfd8ec034333c1
+djangorestframework==3.15.2 \
+    --hash=sha256:2b8871b062ba1aefc2de01f773875441a961fefbf79f5eed1e32b2f096944b20 \
+    --hash=sha256:36fe88cd2d6c6bec23dca9804bab2ba5517a8bb9d8f47ebc68981b56840107ad
     # via
     #   -r requirements.in
     #   django-dbmi-client