style(series/sales/validation.robot): use single form in test names.

No functional changes.

[skip ci]

Author: php-coder

src/test/robotframework/series/sales/validation.robot

@@ -7,13 +7,13 @@ Suite Teardown   After Test Suite
 Force Tags       series  sales  validation
 
 *** Test Cases ***
-Create series sales with too long url
+Create series sale with too long url
 	${letter}=              Set Variable  j
 	Input Text              id=url  http://${letter * 255}
 	Submit Form             id=add-series-sales-form
 	Element Text Should Be  id=url.errors  Value is greater than allowable maximum of 255 characters
 
-Create series sales with invalid url
+Create series sale with invalid url
 	Input Text              id=url  invalid-url
 	Submit Form             id=add-series-sales-form
 	Element Text Should Be  id=url.errors  Value must be a valid URL