test(url_test): disable no-self-assign rule

[magurotuna]

As reported in #7193, linting by the new version of deno_lint produces the error like:

(no-self-assign) "pathname" is assigned to itself
  url.pathname = url.pathname;
                 ~~~~~~~~~~~~
    at /Users/biwanczuk/dev/deno/cli/tests/unit/url_test.ts:186:17

(no-self-assign) "pathname" is assigned to itself
  url.pathname = url.pathname;
                 ~~~~~~~~~~~~
    at /Users/biwanczuk/dev/deno/cli/tests/unit/url_test.ts:190:17

(no-self-assign) "hash" is assigned to itself
  url.hash = url.hash;
             ~~~~~~~~
    at /Users/biwanczuk/dev/deno/cli/tests/unit/url_test.ts:198:13

And according to @nayeemrmn, these self-assignments are required in order to invoke the setters, so the errors should be ignored.
So I added deno-lint-ignore no-self-assign lines.

[ry]

LGTM - thanks