Run Python 3.4 tests optionally

https://fedoraproject.org/wiki/Changes/RetirePython34

tests/tests.yml

@@ -30,9 +30,9 @@
     - smoke27:
         dir: python/smoke
         run: VERSION=2.7 METHOD=virtualenv ./venv.sh
-    - smoke34:
+    - smoke34_optional:
         dir: python/smoke
-        run: VERSION=3.4 ./venv.sh
+        run: VERSION=3.4 INSTALL_OR_SKIP=true ./venv.sh
     - smoke35:
         dir: python/smoke
         run: VERSION=3.5 ./venv.sh
@@ -61,7 +61,6 @@
     - gcc
     - virtualenv
     - python27
-    - python34
     - python35
     - python36
     - python37