Recommend Python 3.8+

I'm only using Python 3.8+ anyways, and 3.7 is end of life as of
next month. Some deps start wanting Python 3.8 so let's just bump
it.

.drone.yml

@@ -114,43 +114,4 @@ steps:
   - pip install -r requirements-dev.txt
   - pytest
 
----
-kind: pipeline
-type: docker
-name: python37
-
-steps:
-- name: database
-  image: postgres:14-alpine
-  detach: true
-  environment:
-    POSTGRES_USER: postgres
-    POSTGRES_PASSWORD: postgres
-    POSTGRES_DB: dspacestatistics
-
-- name: setup
-  image: postgres:14-alpine
-  environment:
-    PGPASSWORD: postgres
-  commands:
-  - id
-  - psql --version
-  - sleep 5
-  - pg_isready -h database -U postgres -d dspacestatistics
-  - createuser -h database -U postgres dspacestatistics
-  - psql -h database -U postgres -c "ALTER USER dspacestatistics WITH PASSWORD 'dspacestatistics'"
-  - psql -h database -U postgres -d dspacestatistics < tests/dspacestatistics.sql
-
-- name: test
-  image: python:3.7-slim
-  environment:
-    PGPASSWORD: dspacestatistics
-    DATABASE_HOST: database
-  commands:
-  - id
-  - python -V
-  - apt update && apt install -y gcc git libpq-dev
-  - pip install -r requirements-dev.txt
-  - pytest
-
 # vim: ts=2 sw=2 et