update actions to use ubuntu 20.04 and python container

Author: alistairewj

.github/workflows/mysql.yml

@@ -8,6 +8,7 @@ jobs:
     # only run if PR is approved
     if: github.event.review.state == 'approved'
     runs-on: ubuntu-22.04
+    container: python:3.10
 
     steps:
       - name: Check out repository code

.github/workflows/psql.yml

@@ -7,7 +7,7 @@ jobs:
   mimic-iv-psql:
     # only run if PR is approved
     if: github.event.review.state == 'approved'
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     container: python:3.10
 
     services:

.github/workflows/sqlite.yml

@@ -8,16 +8,12 @@ jobs:
     # only run if PR is approved
     if: github.event.review.state == 'approved'
     runs-on: ubuntu-20.04
+    container: python:3.10
 
     steps:
       - name: Check out repository code
         uses: actions/checkout@v3
 
-      - name: Set up Python
-        uses: actions/setup-python@v4
-        with:
-          python-version: '3.10'
-
       - name: Python dependencies
         run: |
           pip install pandas