Move group of Qiskit Cold Atom (#720)

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### Summary

As per maintainer suggestion.

ecosystem/resources/members/qiskit-cold-atom.toml

@@ -8,5 +8,5 @@ labels = [ "Physics",]
 created_at = 1678827878.507531
 updated_at = 1678827878.507532
 stars = 26
-group = "provider"
+group = "applications"
 documentation = "https://qiskit-community.github.io/qiskit-cold-atom/"