Fix lookup_value_regex handling of non string types

[lotvall]

I was playing around with a very naive fix for #1316

However I did run into some issues:

Breaking regression tests:

drf-spectacular/tests/test_regressions.py

Line 2430 in 0dea78c

def test_path_parameter_priority_matching(no_warnings, path_func, path_str, pattern, parameter_types):

And this test looks like it would be affected as well as it strips the UUID information:

drf-spectacular/tests/contrib/test_drf_nested_routers.py

Lines 91 to 94 in 0dea78c

	reverse_transforms=[
	lambda x: x.replace('format: uuid', 'pattern: ^[0-9]+$'),
	lambda x: x.replace('\n description: A UUID string identifying this root.', '')
	]

I would be happy to proceed with this PR and make the solution robust, but any early feedback on the issue and advice on the regressions would be appreciated before proceeding!

[lotvall]

I didn't proceed with this, but it would be interesting here to keep this information for UUID's as well, as it would expose more correct information to Open API.

  /root/{id}/:
    get:
      operationId: root_retrieve
      parameters:
      - in: path
        name: id
        schema:
          type: string
          format: uuid
        description: A UUID string identifying this root.
        required: true

Another approach that's adds pattern without removing format and description, but would be good to know if it's spec compliant:

        schema:
          type: string
          format: uuid
          pattern: [0-9]+
        description: A UUID string identifying this root.