[options] should also be conditions

[mrexodia]

Currently you need to do extra work:

[options]
PROJECT_BUILD_TESTS = false

[conditions]
tests = "PROJECT_BUILD_TESTS"

[target.tests]
condition = "tests"
sources = ["src/tests.cpp"]

This could be:

[options]
PROJECT_BUILD_TESTS = false

[target.tests]
condition = "PROJECT_BUILD_TESTS"
sources = ["src/tests.cpp"]