Fix/dependabot ignore python (#458)

* ⬆️ Configure dependabot to ignore Python version updates

Python version should be constrained by the anaconda distribution version
specified in environment.yml, not updated independently by dependabot.

* Fix dependabot python ignore rule to include versions constraint

Author: mmcky

.github/dependabot.yml

@@ -23,3 +23,4 @@ updates:
         versions: [">=2.0"]
       - dependency-name: "python"
         # Python version should be constrained by the anaconda distribution version
+        versions: [">0"]