Add missing include chrono in Event.hh header

[traversaro]

🦟 Bug fix

Fixes the missing include of <chrono> in Event.hh that uses std::chrono.

Summary

<chrono> was not included in Event.hh, even if std::chrono was used there. Probably this went unnoticed due to transitive includes in the standard libraries, but in the new Visual Studio 17.13 this stopped working, probably due to a changes in the transitive includes. Anyhow, it make sense to add it to follow IWYU.

Checklist

• Signed all commits for DCO
• Added tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[ahcorde]

https://github.com/Mergifyio gz-common5

[mergify]

gz -common5

❌ Sorry but I didn't understand the command. Please consult the commands documentation 📚.

[ahcorde]

https://github.com/Mergifyio backport gz-common5

[mergify]

backport gz-common5

✅ Backports have been created

• Backport to branch gz-common5 not needed, change already in branch gz-common5

[traversaro]

https://github.com/Mergifyio backport gz-common5

Apparently the vcpkg team already did the fix in #655, it was simply not forward propagated.