fix: resolve shebang parse error in deno doc --test

[MujahedSafaa]

This PR addresses the issue reported in https://github.com/denoland/deno/issues/26018.

Issue: Running deno doc --test on a file that contains a shebang results in a parse error.

Solution: The bug has been fixed by updating the regex to ensure that the shebang characters (#!) are no longer excluded. This allows the shebang to be retained and parsed correctly. @bartlomieju @dsherret