Remove testing of retired python3.8 from the CI

See https://fedoraproject.org/wiki/Changes/RetirePython3.8

[skip changelog]

(cherry picked from commit d681b5b429)

tests/tests.yml

@@ -13,9 +13,6 @@
     - smoke36:
         dir: python/smoke
         run: VERSION=3.6 TOX=false ./venv.sh
-    - smoke38:
-        dir: python/smoke
-        run: VERSION=3.8 ./venv.sh
     - smoke39:
         dir: python/smoke
         run: VERSION=3.9 ./venv.sh
@@ -34,9 +31,6 @@
     - smoke314:
         dir: python/smoke
         run: VERSION=3.14 ./venv.sh
-    - smoke38_virtualenv:
-        dir: python/smoke
-        run: VERSION=3.8 METHOD=virtualenv ./venv.sh
     - smoke39_virtualenv:
         dir: python/smoke
         run: VERSION=3.9 METHOD=virtualenv ./venv.sh
@@ -72,7 +66,6 @@
     - gcc
     - virtualenv
     - python3.6
-    - python3.8
     - python3.9
     - python3.10-devel
     - python3.11-devel