fix(share_plus): relax win32 dependency constraint

[GianSandoval5]

Description

This PR relaxes the win32 dependency constraint in share_plus from ^6.0.1 to >=5.15.0 <7.0.0.

The current constraint requires win32 6.x, which prevents share_plus from resolving alongside packages that still depend on win32 5.x, such as recent file_picker versions. This change allows both win32 5.15.x and 6.x, improving dependency compatibility without changing plugin behavior.

Related Issues

No related issue.

Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• I titled the PR using Conventional Commits.
• I did not modify the CHANGELOG.md nor the plugin version in pubspec.yaml files.
• All existing and new tests are passing.
• The analyzer (flutter analyze) does not report any problems on my PR.

Breaking Change

Does your PR require plugin users to manually update their apps to accommodate your change?

• Yes, this is a breaking change (please indicate that with a ! in the title as explained in Conventional Commits).
• No, this is not a breaking change.

[GianSandoval5]

The Android integration test did not reach the package tests. It failed while booting the GitHub Actions emulator:

Error: Timeout waiting for emulator to boot.

This looks like a CI/emulator startup issue rather than a failure caused by this dependency constraint change.

[GianSandoval5]

Cerrado porque el paquete requiere más cambios al agregar >=5.15.0 <7.0.0