Update CI to use ubuntu-22.04 and Python 3.7

Signed-off-by: ko-zu <causeless@gmail.com>

Author: ko-zu

.github/workflows/citest.yml

@@ -10,13 +10,13 @@ on:
 
 jobs:
   test-oldpython:
-    runs-on: "ubuntu-20.04"
+    runs-on: "ubuntu-22.04"
     steps:
       - uses: actions/checkout@v4
-      - name: Set up Python 3.5
+      - name: Set up Python 3.7
         uses: actions/setup-python@v5
         with:
-          python-version: "3.5"
+          python-version: "3.7"
         env:
           PIP_TRUSTED_HOST: "pypi.python.org pypi.org files.pythonhosted.org"
           # workaround for certificate incompatibility