fixes flaky spec

Maybe using `build` instead of `create` was confusing the spec

spec/models/geozone_spec.rb

@@ -1,6 +1,6 @@
 require 'rails_helper'
 
-RSpec.describe Geozone, type: :model do
+describe Geozone do
   let(:geozone) { build(:geozone) }
 
   it "should be valid" do
@@ -13,6 +13,8 @@ RSpec.describe Geozone, type: :model do
   end
 
   describe "#safe_to_destroy?" do
+    let(:geozone) { create(:geozone) }
+
     it "is true when not linked to other models" do
       expect(geozone.safe_to_destroy?).to be_truthy
     end