Clarify GDAL version requirement

[cottsay]

🦟 Bug fix

Summary

The default behavior of pkg-config seems to be an exact version match.

This was discovered when the RPM build process automatically added package dependencies based on the *.pc files generated by the project, one of which contained gdal = 3.0. This bug can be confirmed on any distro that has a gdal version other than 3.0, such as Ubuntu Jammy:

$ pkg-config --cflags gz-common5-geospatial
Package 'gz-common5-geospatial' requires 'gdal = 3.0' but version of gdal is 3.4.1
$ echo $?
1

It's interesting that the version comparison behaves differently in the first dependency level (which did not produce an error) than it does in subsequent levels. Perhaps there is a bug in gz-cmake as well.

Checklist

• [x] 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.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (0b8428a) 83.65% compared to head (f6372e4) 83.65%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## gz-common5 #574 +/- ## =========================================== Coverage 83.65% 83.65% =========================================== Files 90 90 Lines 10273 10273 =========================================== Hits 8594 8594 Misses 1679 1679 ```

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