qt6: fix link on windows

[ericLemanissier]

fixes #5844

Specify library name and version: qt/6.*

---

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the
  conan-center hook activated.

[ghost]

I detected other pull requests that are modifying qt/6.x.x recipe:

• [qt6] fix compilation of qt6 with_vulkan on MacOs #6835

This message is automatically generated by https://github.com/ericLemanissier/conan-center-conflicting-prs so don't hesitate to report issues/improvements there.

[conan-center-bot]

All green in build 2 (f49db5149fb3ab3b2b2baeb1dd75219c7111abb7):

• qt/6.0.4@:
  All packages built successfully! (All logs)

• qt/6.1.0@:
  All packages built successfully! (All logs)

• qt/6.1.1@:
  All packages built successfully! (All logs)

• qt/6.1.2@:
  All packages built successfully! (All logs)