build(deps): bump django from 2.2 to 2.2.28 in /.kokoro

Bumps [django](https://github.com/django/django) from 2.2 to 2.2.28.
- [Commits](django/django@2.2...2.2.28)

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

Signed-off-by: dependabot[bot] <support@github.com>

.kokoro/requirements.in

@@ -1,7 +1,7 @@
 # Library specific extra installations.
 # Extra installations are required to ensure all documentation can be
 # generated and not missed out with the generate-docs script.
-django==2.2
+django==2.2.28
 google-cloud-aiplatform[prediction]
 googleapis-common-protos==1.58.0 # pinned for conflict in range specifier.
 grpcio-status==1.48.2 # must be pinned due to protobuf compatibility.

.kokoro/requirements.txt

@@ -158,9 +158,9 @@ distlib==0.3.6 \
     --hash=sha256:14bad2d9b04d3a36127ac97f30b12a19268f211063d8f8ee4f47108896e11b46 \
     --hash=sha256:f35c4b692542ca110de7ef0bea44d73981caeb34ca0b9b6b2e6d7790dda8f80e
     # via virtualenv
-django==2.2 \
-    --hash=sha256:7c3543e4fb070d14e10926189a7fcf42ba919263b7473dceaefce34d54e8a119 \
-    --hash=sha256:a2814bffd1f007805b19194eb0b9a331933b82bd5da1c3ba3d7b7ba16e06dc4b
+django==2.2.28 \
+    --hash=sha256:0200b657afbf1bc08003845ddda053c7641b9b24951e52acd51f6abda33a7413 \
+    --hash=sha256:365429d07c1336eb42ba15aa79f45e1c13a0b04d5c21569e7d596696418a6a45
     # via -r requirements.in
 docker==6.0.0 \
     --hash=sha256:19e330470af40167d293b0352578c1fa22d74b34d3edf5d4ff90ebc203bbb2f1 \
@@ -746,10 +746,6 @@ secretstorage==3.3.3 \
     --hash=sha256:2403533ef369eca6d2ba81718576c5e0f564d5cca1b58f73a8b23e7d4eeebd77 \
     --hash=sha256:f356e6628222568e3af06f2eba8df495efa13b3b63081dafd4f7d9a7b7bc9f99
     # via keyring
-setuptools==67.0.0 \
-    --hash=sha256:883131c5b6efa70b9101c7ef30b2b7b780a4283d5fc1616383cdf22c83cbefe6 \
-    --hash=sha256:9d790961ba6219e9ff7d9557622d2fe136816a264dd01d5997cfc057d804853d
-    # via -r requirements.in
 six==1.16.0 \
     --hash=sha256:1e61c37477a1626458e36f7b1d82aa5c9b094fa4802892072e49de9c60c4c926 \
     --hash=sha256:8abb2f1d86890a2dfb989f9a77cfcfd3e47c2a354b01111771326f8aa26e0254