Fixed incorrect regular plural for -ves words

Fixes singularization for words like caves (cave), staves (staff).
Merge branch '2.3' into 2.4

* 2.3:
  [Form] Automatically add step attribute to HTML5 time widgets to display seconds if needed
  Fixed incorrect regular plural for -ves words
Merge branch '2.4'

* 2.4:
  [Form] Automatically add step attribute to HTML5 time widgets to display seconds if needed
  Fixed incorrect regular plural for -ves words
  [HttpKernel] Replace sha1 with sha256 in recently added tests.