Trailing `.0` is removed from `Float#to_s` and `Float#inspect` at
9d08025b. However, I think the more human-readable format is better
for `Float#inspect`.

For example, in the `Float#to_s` format, the failure message is not
well understood when testing values including types by `eql?` (e.g.
`Numeric#step` test).

  ```ruby
  assert "example" do
    exp = 1.0
    act = 1
    assert_operator(exp, :eql?, act)  #=> Expected 1 to be eql? 1.
  end
  ```