Accept arbitrary capitalization for coverage build type

[azeey]

🦟 Bug fix

Summary

When running cmake -DCMAKE_BUILD_TYPE=coverage (which most of our CI does), gz-cmake generates a warning

Code coverage results with an optimized (non-Debug) build may be misleading

This is only because we are specifically looking for Coverage, with uppercase C. This patch makes it possible to pass any capitalization of the word.

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.

[scpeters]

I tried to reproduce the warning in #437 but found that our test builds of the examples have the possibility of using the Coverage build type, but it doesn't ever seem to happen in our CI because lcov isn't installed, but this change looks good to me so I'll approve it

[azeey]

FYI, you can see the warning in https://github.com/gazebosim/gz-fuel-tools/actions/runs/10014645331/job/27684714954?pr=427 if you expand the cmake section. And this has been the case for older versions of gz-cmake as well.

[azeey]

@Mergifyio backport gz-cmake3 ign-cmake2

[mergify]

backport gz-cmake3 ign-cmake2

✅ Backports have been created

• #438 Accept arbitrary capitalization for coverage build type (backport #435) has been created for branch gz-cmake3
• #439 Accept arbitrary capitalization for coverage build type (backport #435) has been created for branch ign-cmake2