resource_auditor.rb: Skip https audit for curl dependencies

The error message to be fixed:

```console
% brew audit --strict --online xz
xz
  * Stable: The source URL http://downloads.sourceforge.net/project/lzmautils/xz-5.8.1.tar.gz should use HTTPS rather than HTTP
Error: 1 problem in 1 formula detected.

% brew edit xz # change it to https

% brew audit --strict --online xz
xz
  * Stable: should always include at least one HTTP mirror
Error: 1 problem in 1 formula detected.
```

- Fixes #15728

Author: osalbahr

Library/Homebrew/resource_auditor.rb

@@ -151,7 +151,8 @@ def audit_urls
           raise HomebrewCurlDownloadStrategyError, url if
             strategy <= HomebrewCurlDownloadStrategy && !Formula["curl"].any_version_installed?
 
-          if (http_content_problem = curl_check_http_content(
+          # Skip https audit for curl dependencies
+          if !curl_dep && (http_content_problem = curl_check_http_content(
             url,
             "source URL",
             specs:,