[curl] Use sources from GitHub Releases to fix `LIBCURL_VERSION` and `LIBCURL_TIMESTAMP`

[osipxd]

Is your feature request related to a problem? Please describe.

Currently when vcpkg checks out sources from GitHub, LIBCURL_VERSION has suffix "-DEV" and LIBCURL_TIMESTAMP is "[undefined]"
Sources archives provided in GitHub Releases are produced using maketgz script which sets correct version and timestamp.

Proposed solution

Use sources from GitHub Releases instead of checking out a git repository.

Describe alternatives you've considered

No response

Additional context

For example, Conan uses sources from releases to build curl.

[osipxd]

I could try to contribute a fix if you approve the solution