Fix conf-python-3 on Centos

Author: jmid

packages/conf-python-3/conf-python-3.9.0.0/opam

@@ -9,7 +9,8 @@ depexts: [
   ["python3"] {os-family = "debian" | os-family = "ubuntu"}
   ["python3"] {os-distribution = "nixos"}
   ["python3"] {os-distribution = "alpine"}
-  ["python39" "epel-release"] {os-distribution = "centos"}
+  ["python3"] {os-distribution = "centos" & os-version >= "9"}
+  ["python39" "epel-release"] {os-distribution = "centos" & os-version < "9"}
   ["python3"] {os-family = "fedora"}
   ["python3"] {os-distribution = "ol"}
   ["python"] {os-distribution = "arch"}