Use Python 3.10 everywhere

* Bump python from 3.9-slim to 3.10

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

Signed-off-by: dependabot[bot] <[email protected]>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Uxio Fuentefria <[email protected]>

.github/workflows/python.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.9]
+        python-version: ["3.10"]
     services:
       redis:
         image: redis

README.md

@@ -1,7 +1,7 @@
 ![Build Status](https://github.com/gnosis/safe-transaction-service/workflows/Python%20CI/badge.svg?branch=master)
 [![Coverage Status](https://coveralls.io/repos/github/gnosis/safe-transaction-service/badge.svg?branch=master)](https://coveralls.io/github/gnosis/safe-transaction-service?branch=master)
 [![pre-commit](https://img.shields.io/badge/pre--commit-enabled-brightgreen?logo=pre-commit&logoColor=white)](https://github.com/pre-commit/pre-commit)
-![Python 3.9](https://img.shields.io/badge/Python-3.9-blue.svg)
+![Python 3.10](https://img.shields.io/badge/Python-3.10-blue.svg)
 ![Django 3](https://img.shields.io/badge/Django-3-blue.svg)
 
 # Gnosis Transaction Service

docker/web/Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.9-slim
+FROM python:3.10-slim
 
 ARG APP_HOME=/app
 WORKDIR ${APP_HOME}

docker/web/Dockerfile_alpine

@@ -1,5 +1,5 @@
 # Less size than Debian, slowest to build
-FROM python:3.9-alpine
+FROM python:3.10-alpine
 
 ENV PYTHONUNBUFFERED 1
 WORKDIR /app

setup.cfg

@@ -22,7 +22,7 @@ env =
     DJANGO_DOT_ENV_FILE=.env.test
 
 [mypy]
-python_version = 3.9
+python_version = 3.10
 check_untyped_defs = True
 ignore_missing_imports = True
 warn_unused_ignores = True