fix: with_high_message expects a custom validation message too

[freesteph]

The only impact being in the generated documentation (via description_clauses_for_qualifiers):

before:

is expected to validate that Y lies inside the range R

after

is expected to validate that X lies inside the range R producing a
custom validation error on failure

As with_low_message already does.

[matsales28]

Do you mind adding a spec to cover this case?

I think you can do something similar to the one on spec/unit/shoulda/matchers/active_model/validate_numericaly_of_spec.rb

shoulda-matchers/spec/unit/shoulda/matchers/active_model/validate_numericality_of_matcher_spec.rb

Lines 2111 to 2116 in 33bec1c

	it 'describes that it relies upon a strict validation' do
	matcher = validate_numericality_of(:attr).strict
	expect(matcher.description).to eq(
	'validate that :attr looks like a number, raising a validation exception on failure',
	)
	end