Fix(specs): Initialize @version_members in crops/show view spec

The `crops/show` view spec was failing with a `NoMethodError` because
the `@version_members` instance variable was `nil`. This variable is used
in the `_history` partial, which is rendered by the `show` view.

This commit fixes the spec by initializing `@version_members` to an
empty hash in the `before` block of the spec. This ensures that the
view can render without errors during the test run.

spec/views/crops/show.html.haml_spec.rb

@@ -12,6 +12,7 @@ describe "crops/show" do
     @current_member = @member
     @harvest = FactoryBot.create(:harvest, owner: @member)
     controller.stub(:current_user) { @member }
+    assign(:version_members, {})
   end
 
   it "hides sunniness block if no sunniness" do