Bump docker from 4.2.0 to 4.2.1 in /packages/postgres-database (#1541)

Bumps [docker](https://github.com/docker/docker-py) from 4.2.0 to 4.2.1.
- [Release notes](https://github.com/docker/docker-py/releases)
- [Commits](docker/docker-py@4.2.0...4.2.1)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

packages/postgres-database/requirements/_migration.txt

@@ -8,7 +8,7 @@ alembic==1.4.2            # via -r requirements/_migration.in
 certifi==2020.4.5.1       # via requests
 chardet==3.0.4            # via requests
 click==7.1.2              # via -r requirements/_migration.in
-docker==4.2.0             # via -r requirements/_migration.in
+docker==4.2.1             # via -r requirements/_migration.in
 idna==2.9                 # via -r requirements/_base.txt, requests, yarl
 mako==1.1.2               # via alembic
 markupsafe==1.1.1         # via mako

packages/postgres-database/requirements/_test.txt

@@ -15,12 +15,10 @@ chardet==3.0.4            # via -r requirements/_migration.txt, aiohttp, request
 click==7.1.2              # via -r requirements/_migration.txt
 coverage==5.1             # via -r requirements/_test.in, coveralls, pytest-cov
 coveralls==2.0.0          # via -r requirements/_test.in
-docker==4.2.0             # via -r requirements/_migration.txt
+docker==4.2.1             # via -r requirements/_migration.txt
 docopt==0.6.2             # via coveralls
 faker==4.1.0              # via -r requirements/_test.in
-idna-ssl==1.1.0           # via aiohttp
 idna==2.9                 # via -r requirements/_migration.txt, requests, yarl
-importlib-metadata==1.6.0  # via pluggy, pytest
 isort==4.3.21             # via pylint
 lazy-object-proxy==1.4.3  # via astroid
 mako==1.1.2               # via -r requirements/_migration.txt, alembic
@@ -49,11 +47,8 @@ sqlalchemy[postgresql_psycopg2binary]==1.3.17  # via -r requirements/_migration.
 tenacity==6.2.0           # via -r requirements/_migration.txt
 text-unidecode==1.3       # via faker
 toml==0.10.1              # via pylint
-typed-ast==1.4.1          # via astroid
-typing-extensions==3.7.4.2  # via aiohttp
 urllib3==1.25.9           # via -r requirements/_migration.txt, requests
 wcwidth==0.1.9            # via pytest
 websocket-client==0.57.0  # via -r requirements/_migration.txt, docker
 wrapt==1.12.1             # via astroid
 yarl==1.4.2               # via -r requirements/_migration.txt, aiohttp
-zipp==3.1.0               # via importlib-metadata