.drone.yml: don't test on Python 3.7

Pandas 1.4.0 now requires Python 3.8 minimum.

.drone.yml

@@ -26,18 +26,4 @@ steps:
   - apt update && apt install -y gcc g++ libicu-dev pkg-config git
   - pip install -r requirements-dev.txt
 
----
-kind: pipeline
-type: docker
-name: python37
-
-steps:
-- name: build
-  image: python:3.7-slim
-  commands:
-  - id
-  - python -V
-  - apt update && apt install -y gcc g++ libicu-dev pkg-config git
-  - pip install -r requirements-dev.txt
-
 # vim: ts=2 sw=2 et