python 3.9 default for testing

update pre-commit hooks

.gitlab-ci.yml

 #image: registry.esss.lu.se/ics-docker/miniconda
-image: python:3.8-slim
+image: python:3.9-slim
 .pip_install_default: &pip_install_default
     - apt update
     - apt install git -y

.pre-commit-config.yaml

 repos:
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v3.1.0
+    rev: v3.4.0
     hooks:
     - id: end-of-file-fixer
     - id: trailing-whitespace
@@ -15,6 +15,6 @@ repos:
       - id: flake8
         args: ['--max-line-length=140', '--ignore=E203,E402']
   - repo: https://github.com/pre-commit/mirrors-mypy
-    rev: v0.790
+    rev: v0.800
     hooks:
     -   id: mypy