Incorrectly named tests cause some test files to be ignored

When I run `find test -type f ! -name '*_tests.jl'` I see the following: ```bash $ find test/ -type f ! -name '*_tests.jl' test/runtests.jl test/testutilities.jl test/rules/softdot/test_marginals.jl ``` All these files are files that will NOT be tested by ReRuntest.jl as ["test-items must be in files named with the suffix `_test.jl` or `_tests.jl`"](https://github.com/JuliaTesting/ReTestItems.jl?tab=readme-ov-file#running-tests). That is OK for files like `test/runtests.jl` (main test script file) or `test/testutilities.jl` (helper functions). But for test files like `test/rules/softdot/test_marginals.jl` this means they are not included in the test runs when running `make test`! A subsequent `ag test_marginals.jl test/` confirms that the `test_marginals.jl` file is not included as part of any other `@testitem`. Easy fix: Make sure the test files end in the correct suffix.