Minor fixup of the test matrix

 - keep the order of things consistent (legacy after toxenv)
 - don't needlessly set legacy for a py39 job (yet)

Author: hroncok

.github/workflows/main.yml

@@ -39,10 +39,9 @@ jobs:
           - arch: arm64
             toxenv: py310,py311
           - arch: ppc64le
-            legacy: true
             toxenv: py36
-          - arch: ppc64le
             legacy: true
+          - arch: ppc64le
             toxenv: py39,py310,py311
           - arch: s390x
             toxenv: py39,py310,py311