Set range in python codegen default SDK version

If the schema doesn't set any specific dependencies, we should be defaulting to requiring pulumi within the current major version rather than completely unconstrained.

Discussion: https://github.com/pulumi/pulumi-kafka/pull/410/files#r1594324390

pkg/codegen/python/gen.go

@@ -3165,7 +3165,7 @@ func ensureValidPulumiVersion(requires map[string]string) (map[string]string, er
 	// This is just legacy functionality; there's no obvious reason this should be the case.
 	if len(requires) == 0 {
 		result := map[string]string{
-			"pulumi": "",
+			"pulumi": ">=3.0.0,<4.0.0",
 		}
 		return result, nil
 	}