test: pass a hash as intended, not a block

Ruby is readable, except when it is not.

This fixes
     Failure/Error: expect(Yast::SCR).
     ArgumentError:
       wrong number of arguments (0 for 1+)
which is quite cryptic. Running rspec -b/--backtrace reveals the problem
is in and_return.

This probably broke only with RSpec3.

test/network_autoconfiguration_test.rb

@@ -161,11 +161,11 @@ def set(section, key, value)
     expect(Yast::SCR).
       to receive(:Read).
       with(Yast::Path.new(".udev_persistent.net")).
-      and_return {}
+      and_return({})
     expect(Yast::SCR).
       to receive(:Read).
       with(Yast::Path.new(".udev_persistent.drivers")).
-      and_return {}
+      and_return({})
   end
 
   it "configures just one NIC to have a default route" do